Complete amino acid sequence of human placental protein 14: a progesterone-regulated uterine protein homologous to beta-lactoglobulins

β-Lactoglobulin and Glycodelin: Two Sides of the Same Coin?

The two lipocalins, β-lactoglobulin (βLg) and glycodelin (Gd), are possibly the most closely related members of the large and widely distributed lipocalin family, yet their functions appear to be substantially different. Indeed, the function of β-lactoglobulin, a major component of ruminant milk, is still unclear although neonatal nutrition is clearly important. On the other hand, glycodelin has several specific functions in reproduction conferred through distinct, tissue specific glycosylation of the polypeptide backbone. It is also associated with some cancer outcomes. The glycodelin gene, PAEP, reflecting one of its names, progestagen-associated endometrial protein, is expressed in many though not all primates, but the name has now also been adopted for the β-lactoglobulin gene (HGNC, www.genenames.org). After a general overview of the two proteins in the context of the lipocalin family, this review considers the properties of each in the light of their physiological functional significance, supplementing earlier reviews to include studies from the past decade. While the biological function of glycodelin is reasonably well defined, that of β-lactoglobulin remains elusive.

Affinity purification of native glycodelin from amniotic fluid for biological investigations and development of a glycodelin ELISA for clinical studies

INTRODUCTION

Glycodelin is a glycoprotein with different oligosaccharides that are responsible for its diverse biological functions in contraception and immunosuppression. Therefore, it is necessary to have access to adequate amounts of glycodelin with retained carbohydrate structure for functional studies because the carbohydrate part can be lacking or be insufficient in recombinant glycodelin from prokaryotic and eukaryotic cell systems.

METHODS AND RESULTS

Native glycodelin was purified from amniotic fluid by a series of affinity chromatography steps and had many glycosylated forms verified by mass spectrometry. About 7.5 mg glycodelin was obtained from 1.5 L amniotic fluid. No high molecular mass forms of glycodelin were found in amniotic fluid. Aliquots of the purified glycodelin were used as an immunogen in rabbits for antibody production against glycodelin and a calibrator in a highly sensitive glycodelin enzyme-linked immunosorbent assay (ELISA) with a detection limit of about 1 μg/L.

CONCLUSIONS

Native glycodelin was purified from amniotic fluid and used as an immunogen for raising a rabbit antibody against glycodelin and a calibrator in a highly sensitive glycodelin ELISA. We found no high molecular mass forms of glycodelin in amniotic fluid. Aliquots of the purified glycodelin were set aside for functional studies which are in progress.

Investigation on the ability of first trimester glycodelin and angiopoietin-2 to predict small-for-gestational age pregnancies at delivery

BACKGROUND

The aim was to investigate whether first trimester glycodelin and angiopoietin-2 can predict small-for-gestational age (SGA) at delivery, individually or in combination.

METHODS

In this case-control study we measured glycodelin and angiopoietin-2 on serum from 170 singleton pregnant women delivering SGA neonates and 985 singleton pregnant women delivering normal-weighted neonates. All values were converted to multiples of the medians (MoM).

RESULTS

Pregnant women delivering SGA neonates had lower first trimester glycodelin and angiopoietin-2 MoM values [median (interquartile range)] compared with pregnant women delivering normal-weighted neonates for glycodelin: 0.86 (0.58-1.24) vs. 1.03 (0.74-1.45), p<0.001, and for angiopoietin-2: 0.89 (0.69-1.19) vs. 1.01 (0.78-1.31), p<0.001. The prediction performances of the biomarkers showed that the areas under the curve (AUC) were 0.59 (glycodelin), 0.58 (angiopoietin-2), and 0.60 (glycodelin and angiopoietin-2).

CONCLUSIONS

We demonstrated that first trimester glycodelin and angiopoietin-2 were associated with SGA, but they were, individually and in combination, poor predictors of SGA at delivery. The AUCs were low which indicate low detection rates and high false positive rates.

Comparative Proteomics of Human and Macaque Milk Reveals Species-Specific Nutrition during Postnatal Development

Milk has been well established as the optimal nutrition source for infants, yet there is still much to be understood about its molecular composition. Therefore, our objective was to develop and compare comprehensive milk proteomes for human and rhesus macaques to highlight differences in neonatal nutrition. We developed a milk proteomics technique that overcomes previous technical barriers including pervasive post-translational modifications and limited sample volume. We identified 1606 and 518 proteins in human and macaque milk, respectively. During analysis of detected protein orthologs, we identified 88 differentially abundant proteins. Of these, 93% exhibited increased abundance in human milk relative to macaque and include lactoferrin, polymeric immunoglobulin receptor, alpha-1 antichymotrypsin, vitamin D-binding protein, and haptocorrin. Furthermore, proteins more abundant in human milk compared with macaque are associated with development of the gastrointestinal tract, the immune system, and the brain. Overall, our novel proteomics method reveals the first comprehensive macaque milk proteome and 524 newly identified human milk proteins. The differentially abundant proteins observed are consistent with the perspective that human infants, compared with nonhuman primates, are born at a slightly earlier stage of somatic development and require additional support through higher quantities of specific proteins to nurture human infant maturation.

The dimeric crystal structure of the human fertility lipocalin glycodelin reveals a protein scaffold for the presentation of complex glycans

Structural study of human glycodelin, which is involved in reproduction, reveals a homodimeric structure ideally suited as scaffold for the presentation of distinct glycans, whereas bioinformatic analysis indicated exclusive occurrence in suborders of primates that have a menstrual cycle.

Cationic peptides neutralize Ox-LDL, prevent its uptake by macrophages, and attenuate inflammatory response

OBJECTIVE

Apolipoprotein A1 (ApoA1) and apolipoprotein E (ApoE) mimetic peptides have attracted attention due to their ability to reduce atherosclerosis and exhibit antioxidant, anti-inflammatory, and hypolipidemic properties. In this study, we tested whether three distinct and unrelated cationic peptides would inhibit the oxidation of lipoproteins and whether they would counteract and neutralize the negatively charged modified lipoproteins, inhibit their uptake and inflammation by macrophages.

METHODS AND RESULTS

5F-mimetic peptide of ApoA1, LL27 derived from the anti-microbial peptide hCAP, and a human glycodelin derived peptide were commercially synthesized. We noted that these three distinct cationic lysine-rich peptides, two of which were unrelated to any known apolipoproteins, inhibited copper-mediated oxidation of lipoproteins and reduced lipid peroxides in a lysine dependent manner. The peptides also retarded the electrophoretic mobility of previously oxidized LDL and acetylated LDL by virtue of their net positive charge. Pre-incubation of peptides with modified lipoproteins reduced the uptake of the latter by macrophages, thus preventing the formation of foam cells. The cationic peptides inhibited oxidized LDL (Ox-LDL)-induced inflammatory response both in vitro and in vivo.

CONCLUSION

Based on these results, we suggest that in addition to the well known mimetic peptides, other suitable cationic peptides may be of use for controlling Ox-LDL mediated inflammation and atherosclerotic progression.

Mapping the apoptosis inducing domain of an immunomodulatory protein: glycodelin A

Glycodelin A (GdA) is a dimeric glycoprotein synthesized by the human endometrium under progesterone regulation. Based on the high sequence similarity with β-lactoglobulin, it is placed under the lipocalin superfamily. The protein is one of the local immunomodulators present at the feto-maternal interface which affects both the innate as well as the acquired arms of the immune system, thereby bringing about successful establishment and progression of pregnancy. Our previous studies revealed that the domain responsible for the immunosuppressive activity of glycodelin lies on its protein backbone and the glycans modulate the same. This study attempts to further delineate the apoptosis inducing region of GdA. Our results demonstrate that the stretch of amino acid sequence between Met24 to Leu105 is necessary and sufficient to inhibit proliferation of T cells and induce apoptosis in them. Further, within this region the key residues involved in harboring the activity were shown to be present between Asp52 and Ser65.

Glycoprotein and carbohydrate binding protein expression in the placenta in early pregnancy loss

Glycoproteins expressed at the fetal-maternal interface have been shown to exert immunomodulating effects. Glycodelin, hCG and transferrin have been used in in vitro experiments as ligands to block E-selectin-mediated cell adhesion. We found that glycodelin is a strong inhibitor of the E-selectin-mediated cell adhesion with a 10(3)-fold increase in potency compared to the monovalent tetrasaccharide sialyl Lewis X. HCG with distinct carbohydrate expression is also an effective selectin antagonist, whereas the potency of transferrin is low. This could indicate a possible role of glycodelin, hCG and transferrin in preventing leukocyte adhesion to the fetal trophoblast. In decidual tissue of abortion patients, glycodelin expression was significantly reduced compared to normal gestation. These results were confirmed by in situ hybridization. Moreover, glycodelin expression in endometrial cells in vitro could be stimulated by addition of hCG. Because hCG is down-regulated in women with abortion, we speculate that hCG could be one of the factors regulating glycodelin expression. Galectins are structurally related proteins with the ability to bind beta-galactosides through a conserved carbohydrate recognition domain. Galectin-1 (gal-1) expression in the syncytiotrophoblast is down-regulated in early pregnancy loss. Gal-1 recognizes the Thomsen-Friedenreich disaccharide (Galbeta1-3GalNAc-) on the syncytiotrophoblast and extravillous trophoblast. Gal-1 also inhibited trophoblast cell proliferation but did not induce apoptosis in BeWo cells. Ligation of Gal-1 on trophoblast cells may have regulatory effects on trophoblast cell differentiation. Decreased expression of Gal-1 may partly explain disturbed trophoblast differentiation during early placentation leading to early pregnancy loss.

Functional characterization of the progestagen-associated endometrial protein gene in human melanoma

Utilizing gene microarray profiling of melanoma samples, we have recently identified a novel gene overexpressed in both thick primary and metastatic melanomas. This gene, progestagen-associated endometrial protein (PAEP), has never before been implicated in the oncogenic processes of melanoma, with its true function in oncogenesis and tumour progression relatively unknown. Overexpression of the PAEP gene in freshly procured thick primary and metastatic melanoma samples (58%) and daughter cell lines (77%) is confirmed by quantitative RT-PCR, immunohistochemistry, Western blotting and mass spectrometric analysis. We suggest that PAEP gene overexpression is involved with melanoma tumour progression as well as an aggressive phenotype. Transfection of melanoma cells with PAEP small interfering RNA (siRNA) reveals a significant decrease in soft agar colony formation and a marked inhibition of both cell migration and cell invasion. Furthermore, we establish stable melanoma transfectants via PAEP lentiviral small hairpin RNA (shRNA), examine their growth characteristics in a murine xenograft model and reveal that tumour growth is significantly inhibited in two separate melanoma cell lines. Our data strongly implicate the PAEP gene as a tumour growth promoter with oncogenic properties and a potential therapeutic target for patients with advanced melanoma.

The bovine lactation genome: insights into the evolution of mammalian milk

Comparison of milk protein and mammary genes in the bovine genome with those from other mammals gives insights into the evolution of lactation.

Background

The newly assembled Bos taurus genome sequence enables the linkage of bovine milk and lactation data with other mammalian genomes.

Results

Using publicly available milk proteome data and mammary expressed sequence tags, 197 milk protein genes and over 6,000 mammary genes were identified in the bovine genome. Intersection of these genes with 238 milk production quantitative trait loci curated from the literature decreased the search space for milk trait effectors by more than an order of magnitude. Genome location analysis revealed a tendency for milk protein genes to be clustered with other mammary genes. Using the genomes of a monotreme (platypus), a marsupial (opossum), and five placental mammals (bovine, human, dog, mice, rat), gene loss and duplication, phylogeny, sequence conservation, and evolution were examined. Compared with other genes in the bovine genome, milk and mammary genes are: more likely to be present in all mammals; more likely to be duplicated in therians; more highly conserved across Mammalia; and evolving more slowly along the bovine lineage. The most divergent proteins in milk were associated with nutritional and immunological components of milk, whereas highly conserved proteins were associated with secretory processes.

Conclusions

Although both copy number and sequence variation contribute to the diversity of milk protein composition across species, our results suggest that this diversity is primarily due to other mechanisms. Our findings support the essentiality of milk to the survival of mammalian neonates and the establishment of milk secretory mechanisms more than 160 million years ago.

Endometrial protein PP14: a new test of endometrial function?

The human endometrium produces a number of proteins which are at least partly specific to that tissue. Two of these proteins have been the subject of much recent work. They were originally called ‘placental protein 12’ and ‘placental protein 14’ (PP12 and PP14) because they were isolated by Hans Bohn from extracts of whole placentae. However, it is now clear that they arise from the maternal endometrium (decidua) rather than the fetal trophoblast. Placental protein 12 has been shown to be identical to the insulin-like growth factor binding protein-1 (IGFBP-1). It is produced in many normal tissues and its measurement probably does not provide a specific index of endometrial function. By contrast, PP14 is detectable only in ‘reproductive’ tissues and, in theory, might be an excellent clinical test of endometrial function.

Peptides and proteins in the human endometrium

Human endometrium is composed of three layers: stratum compactum, stratum spongiosum and stratum basale. Stratum compactum is the superficial layer made up of openings of the uterine glands and some stromal cells. Stratum spongiosum is the middle layer containing mainly dilated glands and little stroma. Stratum basale is the deepest layer adjoining the muscularis. It consists of primordial glands and compact stroma. Stratum compactum and stratum spongiosum form stratum functionale which is subject to cyclic changes and is removed during menstruation.

Effects of differential glycosylation of glycodelins on lymphocyte survival

Glycodelin is a human glycoprotein with four reported glycoforms, namely glycodelin-A (GdA), glycodelin-F (GdF), glycodelin-C (GdC), and glycodelin-S (GdS). These glycoforms have the same protein core and appear to differ in their N-glycosylation. The glycosylation of GdA is completely different from that of GdS. GdA inhibits proliferation and induces cell death of T cells. However, the glycosylation and immunomodulating activities of GdF and GdC are not known. This study aimed to use ultra-high sensitivity mass spectrometry to compare the glycomes of GdA, GdC, and GdF and to study the relationship between the immunological activity and glycosylation pattern among glycodelin glycoforms. Using MALDI-TOF strategies, the glycoforms were shown to contain an enormous diversity of bi-, tri-, and tetra-antennary complex-type glycans carrying Galbeta1-4GlcNAc (lacNAc) and/or GalNAcbeta1-4GlcNAc (lacdiNAc) antennae backbones with varying levels of fucose and sialic acid substitution. Interestingly, they all carried a family of Sda (NeuAcalpha2-3(GalNAcbeta1-4)Gal)-containing glycans, which were not identified in the earlier study because of less sensitive methodologies used. Among the three glycodelins, GdA is the most heavily sialylated. Virtually all the sialic acid on GdC is located on the Sda antennae. With the exception of the Sda epitope, the GdC N-glycome appears to be the asialylated counterpart of the GdA/GdF glycomes. Sialidase activity, which may be responsible for transforming GdA/GdF to GdC, was detected in cumulus cells. Both GdA and GdF inhibited the proliferation, induced cell death, and suppressed interleukin-2 secretion of Jurkat cells and peripheral blood mononuclear cells. In contrast, no immunosuppressive effect was observed for GdS and GdC.

Glycodelin A, an immunomodulatory protein in the endometrium, inhibits proliferation and induces apoptosis in monocytic cells

Glycodelin A (GdA), is a lipocalin with an immunomodulatory role, secreted by the endometrium under progesterone regulation and proposed to play a role in protecting the fetus from maternal immune attack. Glycodelin A has an inhibitory effect on the proliferation of T cells and B cells and also on the activity of natural killer cells. We have earlier demonstrated that the inhibitory effect of glycodelin A on T cell proliferation is due to apoptosis induced in these cells through the caspase-dependent intrinsic mitochondrial pathway. Studies reported until now have shown that glycodelin modulates the adaptive immune responses. We, therefore, decided to look at its effect, if any, on the innate immune system. The effect of glycodelin on monocytes was studied using human monocytic cell lines, THP1 and U937, and primary human monocytes as model systems. We demonstrated that glycodelin inhibited the proliferation of THP1 and U937 and induced apoptosis in these cells as well as in primary monocytes. We found that this signaling was caspase-independent but followed the intrinsic mitochondrial pathway of apoptosis. No effect of glycodelin was seen on the phagocytic ability of monocytes post-differentiation into macrophages. These observations suggest that, at the fetomaternal interface, glycodelin plays a protective role by deleting the monocytes that could become pro-inflammatory. Importantly, leaving the macrophages untouched to carry on with efficient clearance of the apoptotic cells.

Immunohistochemistry, glycosylation and immunosuppression of glycodelin in human ovarian cancer

Glycodelins (Gds) are glycoproteins with a gender specific glycosylation. Glycodelin A (GdA) is primarily produced in endometrial and decidual tissue and secreted to amniotic fluid. Glycodelins were also identified in several cancer types, including serous ovarian cancer. Gds act as a T-cell inhibitor and are involved in inactivation of human monocytes. With a Gd peptide antibody, derived from a 15 amino acid sequence of human Gd and in situ hybridization experiments, the expression of Gd in serous, mucinous, endometrioid and clear cell ovarian tumors was identified. In contrast to former investigations with antibodies against GdA, a positive immunohistochemical reaction for Gd was observed in all forms of epithelium ovarian cancer. These results were confirmed with in situ hybridization. In addition, Gd is expressed in granulose cell tumors, a non-epithelial form of ovarian cancer. Furthermore, Gd was purified from ascites fluid of ovarian cancer patients. Ascites Gd showed significant differences in its structure of sialyl Lewis-type oligosaccharides compared to GdA. Additionally, ascites Gd inhibits IL-2 stimulated proliferation of peripheral blood leucocytes and inhibits adhesion of SLe(X)-positive cells to E-selectin. Therefore, Gd could act as an inhibitor of lymphocyte activation and/or adhesion in ovarian cancer.

Differential sialylation regulates the apoptotic activity of glycodelin A

Glycodelin A (GdA), a dimeric lipocalin, expressed by the uterine endometrium, is an immunomodulatory agent and induces apoptosis in T-cells. In this study we demonstrate that two populations of GdA with subtle differences in their net ionic charge are present in the amniotic fluid and that, apoptotic activity is exhibited only by the population with more sialic acid residues. Significantly, removal of sialic acid residues from the active populations of GdA abrogates the activity of the molecule, suggesting that the extent of sialylation might be a factor regulating the activity of GdA.

Glycosylation related actions of glycodelin: gamete, cumulus cell, immune cell and clinical associations

Glycodelin is an example of a glycoprotein whose complex-type glycans mediate biological actions in human reproduction and immune reactions. Being attached to an identical protein backbone, glycodelin oligosaccharides vary significantly from one reproductive tissue to another and have an effect on its own secretion and role in cell communication. For instance, uterine glycodelin-A inhibits sperm-oocyte interaction by binding on the sperm head. This is a glycosylation-dependent phenomenon, in which fucosyltransferase-5 plays a key role. Glycodelin-S from seminal plasma binds evenly around the sperm head and maintains an uncapacitated state in the spermatozoa, until the isoform is detached during sperm passage through the cervix. Glycodelin-F from follicular fluid and Fallopian tube binds to the acrosomal region of the sperm head, thereby inhibiting both the sperm-oocyte binding and premature progesterone-induced acrosome reaction. The cumulus cells surrounding the oocyte can capture glycodelin-A and -F from the surrounding environment and convert these isoforms to a cumulus cell isoform, glycodelin-C. It differs by glycosylation from the other isoforms, and it too attaches on the sperm head, with the highest density in the equatorial region. Glycodelin-C is capable of detaching the sperm-bound inhibitory isoforms so that the sperm-oocyte binding is enhanced. Glycodelin-A also has immunosuppressive actions directed to cellular, humoral and innate immunity. Although these actions depend mainly on the protein backbone, glycosylation also plays a part. Glycosylated glycodelin may be involved in the protection of spermatozoa against maternal immune reactions, and glycodelin also has apoptogenic activity. Some glycosylation patterns of glycodelin may mask its apoptogenic domain. This review updates the recent research and clinical associations of glycodelin, highlighting the role of glycosylation.

Roles of glycodelin in modulating sperm function

Glycodelin is a glycoprotein with three well-defined isoforms. They are named as glycodelin-S, glycodelin-A and glycodelin-F. The three isoforms have similar protein core but different carbohydrate moieties. Glycodelin-S is abundant in the human seminal plasma. It suppresses sperm capacitation and in doing so, it maintains the spermatozoa in an uncapacitated state before they enter into the uterine cavity. Glycodelin-A is abundant in the amniotic fluid. It is also secreted from endometrial glands into uterine fluid and is produced by the fallopian tube. Glycodelin-A is the first endogenous glycoprotein that was found to inhibit the binding of spermatozoa to the zona pellucida. The immunosuppressive properties of glycodelin-A suggest that the molecule may protect the spermatozoa from immune attack in the maternal reproductive tract. Glycodelin-F was first found in the follicular fluid, hence its name. It also inhibits spermatozoa-zona pellucida binding. In addition, glycodelin-F suppresses progesterone-induced acrosome reaction, and may serve to prevent premature acrosome reaction. Preliminary findings suggest possible presence of yet another glycodelin isoform in the extracellular matrix of cumulus oophorus. Unlike glycodelin-A and -F, it stimulates spermatozoa-zona pellucida binding. In summary, different isoforms of glycodelin have different biological roles on sperm function, and they act in succession to contribute to the success of fertilization.

Development and characterization of monoclonal antibodies for the immunohistochemical detection of glycodelin A in decidual, endometrial and gynaecological tumour tissues

AIMS

Glycodelin is a glycoprotein with a molecular weight of 28 kDa. Unusual LacdiNAc structures have been identified on glycodelin A, isolated from amniotic fluid. Three major functions of this glycoprotein have been identified. Glycodelin is an immunosuppressive molecule, a marker of morphological differentiation, and a contraceptive. Because no monoclonal antibodies for glycodelin A are commercially available, our aim was to develop and characterize three monoclonal antibodies against this glycoprotein.

METHODS AND RESULTS

Glycodelin A was purified from amniotic fluid by three chromatographic steps and its purity was checked by SDS-PAGE. Antibodies were generated from immunized BALB/c mice. Three IgG1 monoclonal antibodies detecting glycodelin A were cloned. All three antibodies recognized carbohydrate structures of glycodelin A and did not cross-react with glycodelin S. They are applicable to immunohistochemistry (frozen and paraffin sections), ELISA and Western blots.

CONCLUSION

The new antibodies can be used for the detection of glycodelin A in frozen and paraffin-embedded decidual and endometrial tissue. One antibody (A87-B/D2) can be used for the detection of glycodelin in endometrial and ovarian tumour tissues. Because glycodelin A is a major secretory endometrial product during the luteal phase, in early pregnancy and in gynaecological tumours, the new antibodies are, potentially, valuable tools for the study of endometrial development and tumour progression.

Meet the multifunctional and sexy glycoforms of glycodelin

Glycodelin, a human-secreted glycoprotein that appears in a small number of glycoforms, exhibits diverse biological activities, such as in contraception and immunosuppression. Moreover, different tissue-specific glycoforms appear to mediate diverse functions. Quite unusually, the glycodelin N-linked glycans differ between the male and female glycoforms. The fact that these glycans are fundamental for exerting the physiological activities of the different glycoforms, makes them an interesting target for glycobiology research. This review will focus on the involvement of the glycans in glycodelin activity and compare between the several glycoforms.

Stimulation of hCG protein and mRNA in first trimester villous cytotrophoblast cells in vitro by glycodelin A

AIM

Human chorionic gonadotropin (hCG) is produced by fetal trophoblast cells and secreted into maternal circulation mainly in the first trimester of pregnancy. Another glycoprotein, glycodelin A, is one of the main products of the maternal decidua during this period. The purpose of this study was to investigate the effect of glycodelin A on hCG release by isolated cytotrophoblast cells in vitro.

METHODS

Cytotrophoblast cells were prepared from human first trimester placenta and incubated with varying concentrations of glycodelin A. Supernatants were assayed for hCG protein concentrations, and quantification of beta hCG mRNA was carried out by RT-PCR. Expression of hCG was analysed in stimulated trophoblast cells and in unstimulated controls by immunocytochemistry.

RESULTS

Glycodelin A induces a dose-dependent increase of hCG production. An increase of hCG expression was measured at 100 and 200 microg/mL glycodelin-A treatment in trophoblast cell culture by TaqMan assay on mRNA level. We found a moderate staining of hCG in control trophoblast cells, whereas a strong hCG staining was seen in glycodelin A-treated trophoblast cells.

CONCLUSIONS

HCG is a marker for the differentiation process of trophoblast cells. Our results suggest that glycodelin A secreted by the decidualized endometrium is involved in the regulation of hormones produced by the trophoblast.

Immunolocalization of glycodelin in the genital tract of rats

Glycodelin, also known as placental protein 14 has been predominantly localized to organs of the human genital tract. Unfortunately the physiological role of glycodelin is largely unknown since it depends on limited availability of tissues. Therefore, a suitable animal model to study the role of glycodelin would be desirable. Previously, it was shown that glycodelin mRNA is expressed in the genital tract of male and female rats. In the present study, we demonstrate the expression of glycodelin protein in male and female rats by immunohistochemistry and Western blot analysis. For this purpose a polyclonal antibody was generated against glycodelin peptide. In female rats, glycodelin was found in the epithelial gland cells of the uterus, epithelial cells of the fallopian tube as well as in corpora lutea, interstitial and theca cells of the ovary. Glycodelin was distributed in all epithelial cells of the epididymis and the seminal vesicle. In the seminiferous epithelium, glycodelin was seen in all developmental stages of spermatogonia and spermatocytes and in Sertoli cells. Whereas in the rat male reproductive tract glycodelin expression is slightly different from human or primate tissues, in organs of the rat female genital tract glycodelin expression is similar to humans and primates.

Glycodelin responses to hyperinsulinaemic clamp vary according to basal serum glycodelin concentration

OBJECTIVE

Treatment with metformin, an insulin-lowering agent, increases serum glycodelin, a progesterone-regulated lipocalin protein of the reproductive axis that may play a role in foeto-maternal defence mechanisms. This finding led to the hypothesis that insulin might decrease serum glycodelin concentration.

DESIGN, PATIENTS AND MEASUREMENTS

Euglycaemic hyperinsulinaemic clamp experiments (n = 50) were carried out on 28 women of reproductive age (range 25-47 years; mean +/- SEM 39 +/- 1.0 years), and the results were analysed with respect to their baseline serum progesterone (< 10 or > or = 10 nmol/l) and glycodelin (< 10 or > or = 10 microg/l, equivalent to < 357 or > or = 357 pmol/l) concentrations at the onset of the clamp. Ten clamp experiments were performed on five women wearing a levonorgestrel-releasing intrauterine device (IUD), and these were analysed as a separate group.

RESULTS

Contrary to the hypothesis, no acute glycodelin-lowering effect of insulin was found in any of the groups studied. All the small rises in glycodelin levels detected during acute hyperinsulinaemia occurred in the comparisons of medians and not means, and all such changes took place within the limits seen in the women with no progesterone exposure. In the group with low progesterone/low glycodelin (n = 21), glycodelin showed a small but significant increase at 30 and 90 min of the clamp (P < 0.01). In the group with elevated progesterone/low glycodelin (n = 11), there was a slight glycodelin increase at 30 min (P < 0.05), whereas no increase was found in the group with elevated glycodelin levels (n = 8). In the clamp experiments on women with levonorgestrel-releasing IUD, the basal glycodelin level was low in all cases and, as in the other women with low glycodelin levels, glycodelin was slightly increased at 30, 60 and 90 min of hyperinsulinaemia (P < 0.01).

CONCLUSIONS

The results rule out any acute glycodelin-reducing effects of insulin, although indirect long-term effects mediated by insulin on glycodelin secretion cannot be excluded.

Expression of glycodelin A in decidual tissue of preeclamptic, HELLP and intrauterine growth-restricted pregnancies

During pregnancy, the placenta produces a variety of proteins that are responsible for the establishment of the foeto-maternal tolerance and circulation. The aim of this study was to investigate the expression of glycodelin A (formerly named PP14) in decidual tissue of placentas with intrauterine growth restriction (IUGR), preeclamptic patients, hemolysis, elevated liver, low-platelet (HELLP) patients and normal decidual tissue. Slides of paraffin-embedded decidual tissue of patients with IUGR, preeclamptic patients, HELLP patients and normal-term placentas were incubated with either polyclonal or monoclonal antibodies against glycodelin A. Staining reaction was performed with the ABC reagent. Intensity of immunohistochemical reaction on the slides was analysed using a semi-quantitative score. In addition, expression of glycodelin mRNA was analysed by in situ hybridisation. Expression of glycodelin A was significantly reduced in decidual cells of placentas with IUGR and HELLP, as investigated with both monoclonal and polyclonal antibodies and in situ hybridisation. However, preeclamptic decidual tissue showed no significantly different expression of intensity of glycodelin mRNA compared with normal placental tissue controls. A reduced expression of glycodelin A by decidual cells seems to be related to IUGR and HELLP. Therefore, glycodelin A might play an important role in the pathogeneses of these diseases.

Advances in uterine protein research: reproduction and cancer

Uterine protein research has advanced from the measurements of specific compounds to detailed analysis of the genes that regulate protein synthesis and build up the complex carbohydrate structures that play important functional roles. Some 80% of all human proteins are glycoproteins. Functional glycomics highlights the importance of glycosylation in glycoprotein function. Glycodelin is a representative example of functional glycomics because its various glycoforms have different functions. In the uterus, synthesis of glycodelin-A is temporally regulated by progesterone. During the estrogen-dominated fertile window, absence of glycodelin synthesis is significant because uterine glycodelin-A potently and dose-dependently inhibits sperm-egg binding, the initial step in fertilization. The anti-fertilization propensity of glycodelin-A during the luteal phase of the cycle is highly glycosylation-dependent, and there is an intricate functional interplay between spermatozoa, zona pellucida and the various glycodelin isoforms present in the uterine fluid, seminal plasma and follicular fluid, respectively. Endometrial glycodelin synthesis can be induced during the fertile window by administration of progestagens, such as in levonorgestrel hormone-releasing IUD and contraceptive implants. Glycodelin can be chemically modified in such a fashion that it blocks the binding site on CD4 for the HIV surface glycoprotein, synthesis of viral gp 120, and infection of peripheral blood mononuclear cells by the primary HIV isolate THA/93/051, thus potentially inhibiting HIV transmission. Now that a cell line producing the contraceptive isoform has been identified by recombinant technology, these findings may have application for locally applied antiviral contraception. Glycodelin also has immunosuppressive properties, suggesting that the recognition mechanisms in immune and reproductive systems may have converged. Given its inhibitory activity on natural killer cells, abundant at the fetomaternal interphase, the high glycodelin concentration at the same site suggests a role in fetomaternal defense mechanisms. This may be relevant in women with recurrent miscarriage, in whom both the serum and uterine fluid glycodelin concentrations are decreased. Experiments on cancer cell lines have demonstrated increased epithelial differentiation by glycodelin cDNA transfection, and also by co-culture of cancer cells with normal stromal cells in the presence of basement membrane components. Both approaches result in glycodelin expression concomitant with decreased cell proliferation and reversion of the malignant phenotype. These results suggest an active role of normal stromal cells, basement membrane components and glycodelin in epithelial differentiation and glandular morphogenesis. This disposition of glycodelin is significant in patients with certain carcinomas, in which glycodelin-expressing tumors carry better prognosis than glycodelin-negative tumors of the same clinical stage and histological grade. Research on functional glycomics continues to produce significant information on fundamental aspects of fertilization, implantation, pregnancy and cancer.

Glycodelin A, not glycodelin S, is apoptotically active. Relevance of sialic acid modification

Glycodelin, previously known as PP14 (placental protein-14), is a kernel lipocalin secreted by the glandular epithelium of the endometrium upon progesterone stimulation and by the seminal vesicles. The isoform of the protein present in female reproductive tissue, glycodelin A (GdA), and the male counterpart, glycodelin S (GdS), have identical amino acid sequences, but strikingly different N-linked glycans. It is well documented in literature that GdA is an immunosuppressive protein, and we have shown that this activity is due to its ability to induce apoptosis in activated T cells. The precise role of GdS in seminal plasma is not known. In this study, we report that GdS is not apoptotically active. We observe that the apoptotic activity requires the presence of sialic acid residues on the complex glycans, as in the case of GdA; however, complex glycans of GdS are non-sialylated. We have expressed the wild-type protein in Pichia pastoris, which does not add sialic acid to the secreted proteins, and confirmed our observations that the protein is apoptotically inactive in the non-sialylated form. Our results indicate that differential glycosylation modulates the function of the different glycodelin isoforms.

Human decidual natural killer cells are a unique NK cell subset with immunomodulatory potential

Natural killer cells constitute 50–90% of lymphocytes in human uterine decidua in early pregnancy. Here, CD56^bright uterine decidual NK (dNK) cells were compared with the CD56^bright and CD56^dim peripheral NK cell subsets by microarray analysis, with verification of results by flow cytometry and RT-PCR. Among the ∼10,000 genes studied, 278 genes showed at least a threefold change with P ≤ 0.001 when comparing the dNK and peripheral NK cell subsets, most displaying increased expression in dNK cells. The largest number of these encoded surface proteins, including the unusual lectinlike receptors NKG2E and Ly-49L, several killer cell Ig-like receptors, the integrin subunits α^D, α^X, β1, and β5, and multiple tetraspanins (CD9, CD151, CD53, CD63, and TSPAN-5). Additionally, two secreted proteins, galectin-1 and progestagen-associated protein 14, known to have immunomodulatory functions, were selectively expressed in dNK cells.

Differences in glycosylation and sperm-egg binding inhibition of pregnancy-related glycodelin

Glycodelin is a glycoprotein produced in many glands, particularly those of reproductive tissues. It appears as different glycoforms in amniotic fluid (glycodelin-A) and seminal plasma (glycodelin-S), but only glycodelin-A inhibits gamete adhesion. In the present study, glycodelin from secretory-phase endometrium, first-trimester pregnancy decidua, and midtrimester amniotic fluid was studied with respect to physicochemical properties, including glycosylation patterns and inhibitory activity of sperm-egg binding. Purified glycodelins from all these sources were similar in isoelectric focusing and in lectin immunoassays using lectins from Wisteria floribunda and Sambucus nigra. Likewise, the glycodelins inhibited sperm-egg binding in a dose-dependent manner, as measured by hemizona-binding assay. However, subtle quantitative physicochemical and biological differences were found between glycodelins from different sources as well as within the same tissue/fluid between different individuals. Differences were most pronounced between endometrial glycodelins from nonpregnancy and first-trimester pregnancy. The glycan structures studied by fast-atom bombardment mass spectrometry of individual amniotic fluid glycodelin-A samples also showed interindividual quantitative differences. In conclusion, glycodelins from different female reproductive tract tissues and amniotic fluid share substantial similarity, allowing all of them to be called glycodelin-A. However, these glycodelins exhibit quantitative physicochemical and functional differences between different sources and individuals.

Zona-binding inhibitory factor-1 from human follicular fluid is an isoform of glycodelin

Zona-binding inhibitory factor-1 (ZIF-1), a glycoprotein in human follicular fluid, reduces the binding of spermatozoa to the zona pellucida. ZIF-1 has a number of properties similar to those of glycodelin-A from human follicular fluid. The objective of this study was to compare the biochemical characteristics of these two glycoproteins. N-terminal sequencing and protease-digested peptide mapping showed that ZIF-1 and glycodelin-A have the same protein core. However, these glycoproteins differ in their oligosaccharide chains, as demonstrated by fluorophore-assisted carbohydrate electrophoresis, lectin-binding ability, and isoelectric focusing. ZIF-1 inhibited spermatozoa-zona pellucida binding slightly more than did glycodelin-A and significantly suppressed progesterone-induced acrosome reaction of human spermatozoa. Indirect immunofluorescence staining revealed specific binding of glycodelin-A and ZIF-1 to the acrosome region of human spermatozoa, where ZIF-1 produced a stronger signal than did glycodelin-A at the same protein concentration. These data suggest that ZIF-1 is a differentially glycosylated isoform of glycodelin that potently inhibits human sperm-egg interaction. Future study on the function role of ZIF-1 would provide a better understanding of the regulation of fertilization in humans.

Glycodelin and amniotic fluid transferrin as inhibitors of E-selectin-mediated cell adhesion

Human amniotic fluid contains a variety of glycoproteins. Several of these substances have been shown to exert immunomodulatory effects. Glycodelin, previously known as placental protein 14, is one of these glycoproteins. It has a unique carbohydrate configuration, consistent with fucosylated LacdiNAc structures that are very unusual for mammals. Oligosaccharides with fucosylated LacdiNAc antennae have previously been shown to block selectin-mediated cell adhesion. Another glycoprotein, human transferrin, is also present in amniotic fluid in relatively high concentrations. This transferrin shows a different glycosylation compared with serum transferrin. Amniotic fluid transferrin carries sialylated Lewis X antigens. Glycodelin and transferrin were isolated from amniotic fluid and for comparison from serum of pregnant women by chromatographic methods. The purified proteins were used as ligands to block E-selectin-mediated HepG2 cell adhesion. Two types of binding assays with distinct receptor accommodations (immobilised E-selectin and activated HUVECs) were used to quantify inhibition efficiencies of the different proteins. We found that glycodelin is a strong inhibitor with a 10(3)-fold potency compared to the monovalent tetrasaccharide sialyl Lewis X whereas the potency of transferrin is rather low.

Binding of zona binding inhibitory factor-1 (ZIF-1) from human follicular fluid on spermatozoa

Previous studies showed that zona binding inhibitory factor-1 (ZIF-1) was the glycoprotein mainly responsible for the spermatozoa zona binding inhibitory activity of human follicular fluid. ZIF-1 has a number of properties similar to glycodelin-A. A binding kinetics experiment in the present study demonstrated the presence of two binding sites of ZIF-1 on human spermatozoa. These binding sites were saturable, reversible, and bound to (125)I-ZIF-1 in a time-, concentration-, and temperature-dependent manner. Glycodelin-A shared one common binding site with ZIF-1 on spermatozoa, and it could displace only 70% of the (125)I-ZIF-1 bound on human spermatozoa. ZIF-1 and glycodelin-A formed complexes with the soluble extract of human spermatozoa. Coincubation of solubilized zona pellucida proteins reduced the binding of ZIF-1 to two complexes of the extract, suggesting that the ZIF-1 binding sites and zona pellucida protein receptors on human spermatozoa were closely related. ZIF-1, but not glycodelin-A, significantly suppressed progesterone-induced acrosome reaction of human spermatozoa. The carbohydrate moieties derived from ZIF-1 reduced the binding of native ZIF-1 on human spermatozoa as well as the zona binding inhibitory activity of the glycoprotein, although the intensity of the effects are lower when compared with the native protein. These effects are not due to the action of the molecules on the motility, viability, and acrosomal status of the treated spermatozoa. Deglycosylated ZIF-1 had no inhibitory effect on both ZIF-1 binding and zona binding capacity of spermatozoa. We concluded that the carbohydrate part of ZIF-1 was critical for the functioning of the glycoprotein.

Identification of genes down-regulated during melanoma progression: a cDNA array study

In order to identify genes relevant for melanoma development, we carried out cDNA array experiments employing an in vitro model of human melanoma progression, consisting of two cell lines: one, LP, derived from a primary melanoma and the other, LM, from its metastatic supraclavicular lymph node. Basic cDNA array data identified 26 genes as down-regulated in the LM cell line. Northern blot analysis confirmed an effective transcriptional down-regulation for five out of 13 genes analyzed. The products of these five genes belong to different functional protein types, such as transcription and translation regulators (Edg-2, eIF-3 p110, and RNPL/RBM3), extracellular communicators (PRSS11) and members of the major histocompatibility complex (beta2-microglobulin). Some previously described differences in expression patterns, such as loss of HLA I, were confirmed by our array data. In addition, we identified and validated for the first time the reduced expression level of several genes during melanoma progression. In particular, reduced Edg-2 gene product expression was also confirmed in a group of 50 primary melanomas and unrelated metastases. In conclusion, comparative hybridization by means of cDNA arrays assisted in identifying a series of novel progression-associated changes in gene expression, confirming, at the same time, a number of previously described results.

Biochemical and functional characterization of the human zona pellucida

A successful interaction between spermatozoa and the zona pellucida is critical for fertilization. This biological step reflects multiple sperm functions, including the acquisition and completion of capacitation, recognition and binding to specific zona pellucida receptors, and induction of the physiological acrosome reaction. The recognition of carbohydrate sequences by complimentary receptors has been demonstrated in gamete interaction in different animal species. It has been proposed that, in the human, sperm binding to the zona pellucida requires a 'selectin-like' interaction. The hemizona assay (a unique internally controlled bioassay that evaluates tight binding of human spermatozoa to the homologous zona pellucida) and advanced methods of carbohydrate analysis have been used to test this hypothesis. Compelling evidence exists to demonstrate that oligosaccharide recognition is also required for specific, tight human gamete binding. The induction of the acrosome reaction using the physiological inducers, i.e. the zona pellucida and progesterone, was also examined. It has also been demonstrated that there is a priming effect of the steroid on the acrosome reaction inducing capacity of the zona pellucida. These studies may allow for a better understanding of human gamete interaction in physiological and pathological situations.

Life Cycle of Decidual Cells

The decisive events in the development of decidual cells (DC) are presented through examples of human and rodent decidua. Human decidua is formed by large decidual cells (LDC), endometrial granulated cells (eGC), and small decidual cells. The LDC form the main type of decidual membranes, which determine the morphological characteristics of the decidua as a tissue. Immediate precursor cells of LDC are located below the basement membrane of the uterine epithelium before and during implantation. At the next stage of differentiation, LDC acquire a spindle-like shape. Rodent LDC form an epithelium-like structure with gland properties at the terminal stage of differentiation. The single-cell structure of human decidua is a derivative of the epithelial organization of rodent decidua. Spindle-like rat LDC are characterized by a high level of protein, RNA, and DNA synthesis and by intensive proliferation. At the beginning of pregnancy, a cell proliferation predominates over cell loss. By Days 12-13 of rat pregnancy LDC loss reaches 80% per day. Terminally differentiated LDC (tLDC) disappear from decidua due to apoptosis. Apoptosis of tLDC and the exhaustion of their precursors account for the disappearance of LDC in the middle of rat pregnancy. Human term decidua is composed of living cells. Human LDC (hLDC) comprise the largest part of human decidual cells (hLDC). hLDC account for 60-90% of hDC but their relative amount can decrease to 35% in the case of significant cell loss under unfavorable conditions. A decrease of LDC is not accompanied by DC proliferation. The lack of ability of decidua to compensate for DC loss suggests DC is a growing type of cell population without cambial cells. LDC function largely by blebbing and budding. Human and rat endometrial granulated cells (eGC) are characterized by a low level of natural killer (NK) activity and a high level of natural suppressor (NS) activity. The combination of NK and NS properties is characteristic of the eGC immunoregulatory function. Other functions of decidua include control of inflammation and trophoblast growth and expansion in the uterus. The life span of decidual cells is limited by pregnancy.

Glycodelin: a major lipocalin protein of the reproductive axis with diverse actions in cell recognition and differentiation

Glycodelin is a glycoprotein that belongs to the lipocalin superfamily. Depending on glycosylation, glycodelin appears in various isoforms. In the uterus, glycodelin-A is the major progesterone-regulated glycoprotein secreted into uterine luminal cavity by secretory/decidualized endometrial glands. The other tissues expressing glycodelin include fallopian tubes, ovary, breast, seminal vesicle, bone marrow, and eccrine glands. Glycodelin-A potently and dose-dependently inhibits human sperm-egg binding, whereas differently glycosylated glycodelin-S from seminal plasma has no such effect. Absence of contraceptive glycodelin-A in the uterus during periovulatory midcycle is consistent with an open "fertile window." Glycodelin induced by local or systemic administration of progestogens may potentially reduce the fertilizing capacity of sperm in any phase of the menstrual cycle. Glycodelin also has immunosuppressive activity. Its high concentration at the fetomaternal interface may contribute to protection of the embryonic semiallograft. Besides being an epithelial differentiation marker, glycodelin appears to play a role in glandular morphogenesis, as transfection of glycodelin cDNA into a glycodelin-negative breast cancer cells resulted in formation of gland-like structures, restricted proliferation, and induction of other epithelial markers. These various properties, as well as the chemistry, biology, and clinical aspects of glycodelin, continue to be areas of active investigation reviewed in this communication.

Glycodelins

Glycodelin is a major glycoprotein that is synthesized in the endometrium in response to progesterone and relaxin exposure. Endometrium-derived glycodelin-A has contraceptive and immunosuppressive properties. Glycodelin is absent from the endometrium during the fertile periovulatory phase, but is synthesized in this tissue during the peri-implantation phase and is abundant during the last week of the luteal phase. Changes in local and/or circulating glycodelin concentrations have been observed in women with reproductive disorders. The chemical modification of glycodelins has resulted in compounds with antiviral activity.

Characterization of glycosylated variants of beta-lactoglobulin expressed in Pichia pastoris

Glycosylated variants of beta-lactoglobulin (BLG) were produced in the methylotrophic yeast Pichia pastoris to mimic the glycosylation pattern of glycodelin, a homologue of BLG found in humans. Glycodelin has three sites for glycosylation, corresponding to amino acids 63-65 (S1), 85-87 (S2) and 28-30 (S3) of BLG. These three sites were engineered into BLG to produce the variants S2, S12 and S123, which carried one, two and three glycosylation sites, respectively. The oligosaccharides on these BLG variants ranged from (mannose)(9)(N-acetylglucosamine)(2) (Man(9)GN(2)) to Man(15)GN(2) and were of the alpha-linked high mannose type. The variant S123 exhibited highest levels of glycosylation, with the range of glycans being Man(9-14)GN(2). Digestion of S123 with alpha-1,2 linkage specific mannosidase resulted in a single product corresponding to Man(6)GN(2). These results indicated a glycosylation pattern consisting of a Man(5)GN(2) structure extended by 4-9 mannose residues attached mainly by alpha-1,2 linkages. The results also indicated extension of the Man(5)GN(2) structure by a single alpha-1,6-linked mannose. The N-linked glycosylation pathway in P.pastoris is significantly different from that in Saccharomyces cerevisiae, with the addition of shorter outer chains to the core and no alpha-1,3 outer extensions.

Platelet immunoregulatory factors

A number of soluble and membrane-associated proteins are known to mediate platelet:leukocyte interactions. Platelet-derived factors that have attracted the most attention to date include transforming growth factor beta, interleukin 1 and platelet factor 4. Recently, we have uncovered another protein within platelets that has leukocyte modulatory activity. It was previously characterized as an endometrial glycoprotein named placental protein 14 (PP14) with suppressive effects upon lymphocyte proliferation, pro-inflammatory cytokine production and natural killer cell function. The "hematopoietic" PP14 derived from cells of the megakaryocytic lineage shares this immunosuppressive property, as evaluated by two-way mixed lymphocyte cultures. Interestingly, two alternatively spliced hematopoietic PP14 mRNAs have been cloned which differ in their encoded proteins. Cell-free translation and transfection analyses have verified the translatability of both PP14 mRNA species and allowed for the analysis of their glycosylation properties. PP14, a member of the lipocalin structural superfamily of proteins, now offers an intriguing new link between the coagulation and immune systems.

Characterization of monoclonal antibodies to glycodelin and recombinant glycodelin

Glycodelin-A belongs to the lipocalin superfamily. Although it is associated with normal endometrial growth during the menstrual cycle, fertilization and normal pregnancy in humans, the molecular mechanism of its biological action has not been elucidated. To undertake studies to understand the functional relevance of any molecule, obtaining large quantities of the protein becomes essential. With the ultimate aim of purifying glycodelin either from its natural sources (human amniotic fluid) or the recombinant glycodelin from bacterial recombinant lysates, we raised monoclonal antibodies to this protein. As immunogens, recombinant glycodelin expressed in E. coli and Pichia pastoris as well as glycodelin from amniotic fluid were used. The monoclonal antibodies generated were characterized with respect to binding to both the native as well as the recombinant proteins using ELISA, immunoblotting, and immunohistochemistry.

Glycodelin: a reproduction-related lipocalin

Glycodelin, a human lipocalin, is a major endometrial protein with at least two differentially glycosylated isoforms. Glycodelin-A (GdA) is purified from human mid-trimester amniotic fluid, where it is secreted from the decidualized endometrium. Glycodelin-S (GdS) is synthesized in the male reproductive tract, mainly in the seminal vesicles, and secreted into seminal plasma. These two glycodelin isoforms, glycosylated in a completely different manner, serve as a good model for studying the effects of glycosylation on protein function and physicochemical properties. We have reviewed here the structure, expression and biological functions of glycodelin.

Clinical applications of serum placental protein 14 (PP14) measurement in the IVF-ET cycle

OBJECTIVE

Placental protein 14 (PP14) is known to be one of the endometrial proteins that reflect endometrial functioning throughout the menstrual cycle. In this study, we examined PP14 as a marker for human endometrial receptivity in order to predict the outcome of in vitro fertilization and the embryo-transfer (IVF-ET) cycle.

PATIENTS AND METHODS

The subjects were 72 women who had 96 IVF-ET cycles and who were examined at Tokyo Medical University Hospital during the period of January 1998 to June 1998 because of mechanical or unexplained infertility for a duration of at least 2 years. Serum samples were collected from all patients during treatment cycles, and serum PP14 concentrations were measured by a newly established enzyme-linked immunosorbent assay (ELISA).

RESULTS

In the pregnant group, serum PP14 concentrations were markedly increased after ET, and a significant difference between the pregnant group and the nonpregnant group was observed 8 days following ET (p < 0.01). PP14 concentrations were higher in patients with endometria that exhibited homogenous patterns and that were more than 7 mm thicker than in other patients, as determined by ultrasound on the day of oocyte collection (p < 0.005). The pregnancy rates of patients with homogeneous patterns were lower than those of patients showing a trilaminar pattern. No pregnancies were observed when serum PP14 concentrations were greater than 6.85 U/l on the day of oocyte collection.

CONCLUSION

PP14 might be a useful marker for human endometrial receptivity to predict the outcome of IVF-ET cycles.

Recombinant glycodelin carrying the same type of glycan structures as contraceptive glycodelin-A can be produced in human kidney 293 cells but not in chinese hamster ovary cells

We have produced human recombinant glycodelin in human kidney 293 cells and in Chinese hamster ovary (CHO) cells. Structural analyses by lectin immunoassays and fast atom bombardment mass spectrometry showed that recombinant human glycodelin produced in CHO cells contains only typical CHO-type glycans and is devoid of any of the N, N'-diacetyllactosediamine (lacdiNAc)-based chains previously identified in glycodelin-A (GdA). By contrast, human kidney 293 cells produced recombinant glycodelin with the same type of carbohydrate structures as GdA. The presence of a beta1-->4-N-acetylgalactosaminyltransferase functioning in the synthesis of lacdiNAc-based glycans in human kidney 293 cells is concluded to be the cause of the occurrence of lacdiNAc-based glycans on glycodelin produced in these cells. Furthermore, human kidney 293 cells were found to be particularly suited for the production of recombinant glycodelin when they were cultured in high glucose media. Lowering the glucose concentration and the addition of glucosamine resulted in higher relative amounts of oligomannosidic-type glycans and complex glycans with truncated antennae. Human glycodelin is an attractive candidate for the development of a contraceptive agent, and this study gives valuable information for selecting the proper expression system and cell culture conditions for the production of a correctly glycosylated recombinant form.

Effect of pH on the structure and aggregation of human glycodelin A. A comparison with beta-lactoglobulin A

The effect of pH on the structure of glycodelin A (GdA) and of beta-lactoglobulin A (beta-LgA) has been investigated by means of circular dichroism, steady state fluorescence, synchrotron radiation small angle X-ray scattering (SR-SAXS) and gel permeation chromatography. The comparison between GdA and beta-LgA shows that, at pH 7.0, both proteins are dimers with an extended content of beta-sheet conformation, but pH 2.0 and 9.0 yield a different secondary, tertiary and quaternary structural organisation. Whilst beta-LgA is a monomer, that conserves beta-sheet conformation at pH 2.0 and 9.0, GdA has a stable dimeric structure at alkaline pH, but at pH 2.0 increases its alpha-helix content and it aggregates soon. SR beam has been used to perform SAXS comparative measurements of the two proteins. SR-SAXS data provide the radius of gyration and the radii of the cross-section and of the thickness. GdA aggregation at acid pH has been characterised by calculating the distance distribution function (P(r)). Isoelectric focusing and chromatofocusing data show a different charge distribution on the surfaces of the two proteins, supporting the hypothesis that the presence of oligosaccharides deeply influences the conformational state and the aggregation process of GdA at different pH values. In particular, the presence of sialic acid residues, within the oligosaccharide moiety of the GdA, might be responsible for the differences observed between the two proteins.

Absolute quantification of human chorionic gonadotropin-beta mRNA with TaqMan detection. 4

We describe a reverse transcriptase-polymerase chain reaction (RT-PCR) for determination of human chorionic gonadotropin-beta (HCG beta) mRNA copies using the TaqMan system. To evaluate our quantitative assay, we analyzed HCG beta transcripts of all protein coding genes (HCG beta 5, 3, 8, and 7) in human RNA panels of different normal tissues and in glycodelin-A-stimulated trophoblast cell cultures. Absolute quantification using HCG beta TaqMan probe was found to be highly reproducible. Our study of RNA panels confirms recently published results that expression of HCG beta transcripts is a common feature of a great variety of different normal tissues. High levels of HCG beta mRNAs (> 1,000 molecules per 200 ng RNA) were detected in placenta, uterus, and testis. An increase of HCG beta mRNA expression (1.7-fold) was detected at 150 micrograms/mL glycodelin-A treatment in trophoblast cell culture. Time-dependence study showed that the increase in HCG beta mRNA level was evident at 60 min after glycodelin-A treatment. In summary, we have developed a highly sensitive one-tube, one-enzyme quantitative RT-PCR system that is time-saving and avoids postamplification procedures.

Expression of glycodelin in human breast and breast cancer

Glycodelin is a 28 kDa glycoprotein with structural homology to beta-lactoglobulins, particularly expressed in steroid-responsive tissues of the female reproductive tract. We previously found that transfection of glycodelin cDNA into MCF-7 breast cancer cells induces differentiation into organized acinar epithelium and up-regulation of epithelial markers. In this study, we used immunohistochemistry, Northern blotting and reverse transcription-polymerase chain reaction (RT-PCR) analyses to study glycodelin expression in normal and in malignant breast tissues. The results were compared with the expression of estrogen (ER) and progesterone receptors (PR) and p53 tumor suppressor protein. Glycodelin was found in ductal and lobular epithelium of 6/6 normal breast tissues, 27/29 morphologically normal breast tissues from breast cancer patients, 6/6 benign lactating adenomas, 21/35 ductal carcinomas, 9/9 tubular carcinomas, 9/9 mucinous carcinomas, 3/3 mixed ductal/tubular carcinomas and 7/11 lobular carcinomas. In the latter, of particular interest was the presence of glycodelin in paranucleolar vacuoles of carcinoma cells. Northern blot analysis of fresh frozen tissues revealed the normal full length 0.9 kb mRNA of glycodelin in ductal breast carcinoma. Using RT-PCR analysis, glycodelin messenger ribonucleic acid was found in 13/13 ductal and in 3/3 tubular tumor tissues. We also detected a splicing variant lacking exon 4, which includes the nucleotide sequence encoding the potential N-glycosylation site at Asn-85. Our results demonstrate the synthesis of glycodelin in normal breast and breast cancer. In addition, we show that the paranuclear vacuole, characteristically present in lobular breast cancer cells, contains abundant amounts of glycodelin.