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PubMedDate not supplied

Linkage of human chorionic gonadotrophin and placental lactogen biosynthesis to trophoblast differentiation and tumorigenesis.

Normal trophoblast of the human placenta elaborates at least two major protein hormones, chorionic gonadotrophin (hCG) and placental lactogen (hPL). Molar and choriocarcinoma tissues characteristically synthesize large amounts of hCG and hPL. To examine the role of trophoblast differentiation in the expression of the hCG and hPL genes, we studied the cytological distribution of their mRNAs in tissue sections of human hydatidiform mole and choriocarcinoma by in situ hybridization. Histologically, these tissues are in different stages of cellular differentiation. In normal placenta, hCG alpha/beta mRNA can be localized to some cytotrophoblasts and primarily to the syncytium, whereas hPL mRNA appears only in the syncytial layer. In hydatidiform mole, which still retains placental villous morphology, the hPL gene and hCG alpha and beta genes are expressed but are poorly localized because of the admixture of cyto- and syncytiotrophoblasts. By contrast, choriocarcinoma, which is devoid of placental villous pattern but in which the cyto- and syncytiotrophoblast-like components are distinguishable, expresses hCG alpha and beta in the syncytial-like areas but little, if any, hPL. These results suggest that a certain level of trophoblast differentiation, such as villous formation, is associated with hPL expression, while the hCG alpha gene and the hCG beta gene can be expressed in more disorganized tissues which contain cytotrophoblastic elements.

Cell Differentiation↗
PubMed1989

Characterizations of two distinct Ca2+-dependent phospholipid-binding proteins of 68-kDa isolated from human placenta.

Two distinct 68-kDa proteins, named 68K-I (pI 6.4) and 68K-II (pI 5.6), were solubilized from human placenta by treatment with 5 mM EGTA. On DE52 cellulose column chromatography at pH 7.4, 68K-I in the EGTA eluate was recovered in the unadsorbed fractions, whereas 68K-II was retained on the column and eluted with 0.2 M NaCl. The 68K-I protein was obtained in more than 95% purity by further hydroxylapatite and cation exchange chromatographies, while the 68K-II protein was purified further by gel filtration and hydroxylapatite chromatographies. Partial amino acid sequence data showed that 68K-I protein was a novel protein which shared the same sequences as lipocortin I and that 68K-II was the same as human p68/67-kDa calelectrin (Crompton, M. R., Owens, R. J., Totty, N. F., Moss, S. E., Waterfield, M.D., and Crumpton, M. J. (1988) EMBO J. 7, 21-27; Südhof, T. C., Slaughter, C. A., Leznicki, I., Barjon, P., and Reynolds, G. A. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 664-668). The two proteins bound to acidic phospholipids, phosphatidylserine, and/or phosphatidylinositol, but not to phosphatidylcholine, in the presence of micromolar levels of Ca2+. 68K-I bound to phosphatidylinositol preferentially to phosphatidylserine, whereas 68K-II bound only to phosphatidylserine. Both 68K-I and 68K-II inhibited phospholipase A2 activity, and the inhibition by 68K-II was detectable only in the presence of 100 mM KCl. 68K-I, but not 68K-II, was found to bind to F-actin in a Ca2+-dependent (1 mM) manner. Moreover 68K-I, but not 68K-II, was phosphorylated in vitro at tyrosine residues by fps kinase and by epidermal growth factor receptor/kinase, the latter reaction being dependent on Ca2+ and epidermal growth factor. Western blot analysis with affinity purified anti-68K-I and anti-68K-II antibodies showed that 68K-I was located in only certain tissues, especially human placenta, whereas 68K-II was present in many human and rat tissues.

Actins↗
PubMed1988

In-vitro steroid synthesis by the placenta of cows in late gestation and at parturition.

Placental tissues were collected during late gestation (Group I, N = 11), pre partum (Group II, N = 9) and post partum (N = 29): 15 of the post-partum cows released the fetal membranes normally (Group III) and 14 retained the fetal membranes (Group IV). Preparations of dispersed fetal placental cells, preparations enriched in binucleate cells (BNC) or in small principal cells as well as tissue minces were utilized. Maternal placental tissue (caruncle) and fetal placental principal cells made minimal conversion of prenenolone and androstenedione to other steroids (less than 15% conversion). Fetal placental tissue and enriched preparations of BNC were more active and were similar in their conversion of pregnenolone and androstenedione to other steroids. BNC converted pregnenolone primarily to progesterone during late gestation, but this was altered in the direction of oestrogens pre partum and post partum. BNC were capable of converting androstenedione to oestrogens, but this ability diminished greatly post partum if the fetal membranes were released normally. In-vitro treatment of fetal placental tissue minces with dexamethasone increased the conversion of pregnenolone to androstenedione and the oestrogens but did not alter the conversion the primary cell type involved in fetal placental steroidogenesis peripartum and that dexamethasone may alter this steroidogenesis by activating the C17,20-lyase enzyme complex.

Androstenedione↗
PubMed1985

Immunoreactive and biologically active growth hormone-releasing factor in the rat placenta.

Rat placentas from fetuses of 18 and 20 days of gestation were collected, extracted, and examined for their capacity to stimulate GH release in vitro. The crude extract stimulated, in a dose-dependent fashion, GH release by rat anterior pituitary cells in monolayer culture. The biological and immunological activities retained on antirat GH-releasing factor immunoaffinity columns eluted on Sephadex G-75 (fine) columns with an estimated mol wt of 5000 daltons. Reverse phase HPLC of this material revealed the presence of two forms of GRF activity that eluted with retention times identical to those of synthetic rat GRF and its methionine sulfoxide counterpart [Met(O)27]GRF. The results demonstrate the presence of an immunoreactive and biologically active GRF in the rat placenta that is indistinguishable from rat hypothalamic GRF.

Animals↗
PubMed1985

Isolation, characterization, and regulation of the prolactin receptor.

The prolactin, or lactogenic hormone, receptor has been purified (approximately 80%) from lactating mouse liver and human term placenta by the nondenaturing zwitterionic detergent 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate and a prolactin affinity column. The isolated "core-binding unit" has a molecular weight of 37,000 +/- 2,000 daltons. It retains the specificity for lactogenic hormones and binds prolactin with an affinity (Ka = 2 to 6 X 10(9) M-1) similar to that of the receptor as it occurs in its membranous environment (Ka = 3 to 5 X 10(9) M-1). Whether this "core-binding unit" exists on the cell surface in a cryptic or active form is influenced greatly by its association with other membrane proteins and the concentration of phosphatidylcholine within its local membranous environment.

Animals↗
PubMedDate not supplied

[The effect of plant oils on the female reproductive system].

The influence of a single dose of different plant oils on the rat estrous cycle and fertility was studied. The ovary function activity was ascertained to be inhibited by soybean, peachy or buckthorn oil injection which resulted in the prolongation of the estrous cycle and its phase destruction. The administration of oil provoked temporal fecundation retain (corn, soybean, sunflower-seed or peachy oils) and decreased the number of pregnant animals (peachy, olive or sunflower-seed oils). The number of the ovary corpus luteum, placentas and living fetus in the uterus were declined, and embryonic death was increased in females after peachy, corn, sunflower-seed, soybean, castor or buckthorn oil feeding. It is concluded that vegetable oils depress ovarian folliculogenesis and have not only anti-implantative, but abortive effects to a greater or lesser extent.

Animals↗
PubMed1996

Hyaluronan, CD44 and its variant exons in human trophoblast invasion and placental angiogenesis.

Both hyaluronan and one of its receptors, CD44, can be demonstrated in the early human conceptus and in placental stroma. The variants of CD44 resulting from variable exon splicing are found in metastasizing human malignancies and are also involved in hyaluronan uptake and degradation. The resulting hyaluronan fragments are known to be highly angiogenic. We postulated that the self-limited process of trophoblast invasion of the uterine decidua results in part from the strategy of alternative splicing of CD44, similar to that used by invasive cancer cells in the course of metastatic spread and possibly angiogenesis. Monoclonal antibodies specific for CD44s and for an exon expressed during metastatic tumour progression, CD44v7, were used to examine this hypothesis. In this study we found human trophoblasts, for the first time, to express CD44. Intermediate trophoblasts of first and second trimester exhibited the standard form of CD44 while extravillous trophoblasts, which are responsible for the invading characteristics of the placenta, were positive for the alternatively spliced form, the CD44v7-8. Moreover, in the case of placenta accreta there was a prominent membrane staining of the trophoblasts that were embedded in the fibrin layer over the myometrium. The highly metastatic choriocarcinoma cells also expressed CD44v7-8. We propose, therefore, that the invading trophoblasts utilize the alternatively splicing machinery. These cells retain their invasive capabilities through the permissive ECM by carrying the CD44v7-8 isoform, which binds weakly to hyaluronan and thus prevents it from being degraded by intracellular hyaluronidase.

Alternative Splicing↗
PubMed1982

A cell spreading factor, abundant in human placenta, contains fibronectin and fibrinogen.

A salt extract from human normal-term placental extracellular matrix contains material that rapidly adsorbs to glass or tissue-culture plastic and promotes the spreading of fibroblastic and epithelioid cell lines. The cellular response to placental spreading factor (PSF) is characterized and compared with the response to fibronectin. The active component is shown to contain antigenic determinants that cross-react with antibodies to fibronectin and fibrinogen. The activity is not retained on gelatin-Sepharose but another component of the extract (approximately 185 000 molecular weight) is retained. Partial purification is reported, and the possible involvement of PSF in trophoblastic invasion of the uterine wall is discussed.

Cell Adhesion↗
PubMed2003

Cyclins E1 and E2 are required for endoreplication in placental trophoblast giant cells.

In mammalian cells, cyclin E-CDK2 complexes are activated in the late G1 phase of the cell cycle and are believed to have an essential role in promoting S-phase entry. We have targeted the murine genes CCNE1 and CCNE2, encoding cyclins E1 and E2. Whereas single knockout mice were viable, double knockout embryos died around midgestation. Strikingly, however, these embryos showed no overt defects in cell proliferation. Instead, we observed developmental phenotypes consistent with placental dysfunction. Mutant placentas had an overall normal structure, but the nuclei of trophoblast giant cells, which normally undergo endoreplication and reach elevated ploidies, showed a marked reduction in DNA content. We derived trophoblast stem cells from double knockout E3.5 blastocysts. These cells retained the ability to differentiate into giant cells in vitro, but were unable to undergo multiple rounds of DNA synthesis, demonstrating that the lack of endoreplication was a cell-autonomous defect. Thus, during embryonic development, the needs for E-type cyclins can be overcome in mitotic cycles but not in endoreplicating cells.

Animals↗
PubMed1983

Cytological distribution of chorionic gonadotropin subunit and placental lactogen messenger RNA in neoplasms derived from human placenta.

Normal trophoblast of the human placenta elaborates at least two major protein hormones, chorionic gonadotropin (hCG), and placental lactogen (hPL). There are several gestational trophoblastic diseases of the placenta called hydatidiform mole, invasive mole, and choriocarcinoma. Molar and choriocarcinoma tissues characteristically synthesize large amounts of hCG and small quantities of hPL. To examine the role of trophoblast differentiation in the expression of the hCG and hPL genes, we studied the cytological distribution of their messenger RNA (mRNA) in tissue sections of human hydatidiform mole and choriocarcinoma by in situ hybridization. Histologically, these tissues are in different stages of cellular differentiation. In normal placenta, hCG alpha and -beta mRNA can be localized to some cytotrophoblasts and primarily to the syncytium, whereas hPL mRNA appears only in the syncytial layer. In hydatidiform mole, which still retains placental villous morphology, the hPL gene and hCG alpha and -beta genes are expressed but are poorly localized because of the admixture of cyto- and syncytiotrophoblasts. By contrast, choriocarcinoma, which is devoid of placental villous pattern but in which the cyto- and syncytiotrophoblast-like components are distinguishable, expresses hCG alpha and -beta in the syncytial-like areas but little, if any, hPL. These results suggest that a certain level of trophoblast differentiation, such as villous formation, is associated with hPL expression, while the hCG alpha gene and the hCG beta gene can be expressed in more disorganized tissues that contain cytotrophoblastic elements.

Cell Differentiation↗
PubMedDate not supplied

Peroxidase: a novel pathway for chemical oxidation in human term placenta.

Hydrogen peroxide-dependent oxidation of xenobiotics in a crude fraction of human term placental membranes (nuclei, mitochondria and microsomes) was investigated. Guaiacol was employed as a model substrate. The rate of its oxidation was found to be dependent on the concentration of protein, H2O2 and the substrate as well as the pH of the buffer. Several other classical substrates for peroxidases from different sources viz. pyrogallol, benzidine, p-PDA, DMBD, ABTS, TMPD and TMBD and endogenous chemicals such as bilirubin and epinephrine were also found to undergo oxidation. The xenobiotic oxidizing capacity of the membranes was retained by CaCl2 (0.5 M) extract as well as by the partially purified enzyme obtained by affinity (Con A) chromatography. The H2O2-dependent chemical oxidation by the partially purified peroxidase was inhibited by NaN3 and KCN (IC50 values 41 and 23 microM respectively). These results suggest that peroxidase may be a major enzyme in human term placenta capable of oxidation of endogenous chemicals and xenobiotics.

Bilirubin↗
PubMed1984

The role of trophoblast differentiation in the control of the hCG and hPL genes.

Normal trophoblast of the human placenta elaborates at least two major protein hormones, hCG and hPL. Molar and choriocarcinoma tissues characteristically synthesize large amounts of hCG and small quantities of hPL. To examine the role of trophoblast differentiation in the expression of the hCG and hPL genes, we studied the cytological distribution of their mRNAs in tissue sections of human hydatidiform mole and choriocarcinoma by in situ hybridization. Histologically, these tissues are in different stages of cellular differentiation. In normal placenta, hCG alpha and hCG beta mRNAs can be localized to some cytotrophoblasts and primarily to the syncytium, whereas hPL mRNA appears only in the syncytial layer. In hydatidiform mole, which still retains placental villous morphology, the hPL gene and hCG alpha and hCG beta genes are expressed but are poorly localized because of the admixture of cyto- and syncytiotrophoblasts. By contrast, choriocarcinoma, which is devoid of placental villous pattern but in which the cyto- and syncytiotrophoblast-like components are distinguishable, expresses hCG alpha and hCG beta in the syncytial-like areas but little, if any, hPL. These results suggest that a certain level of trophoblast differentiation, such as villus formation, is associated with hPL expression, while the hCG alpha gene and the hCG beta gene can be expressed in more disorganized tissues which contain cytotrophoblastic elements.

Cell Differentiation↗
PubMed1995

Characteristics of trophoblast cells migrating from first trimester chorionic villus explants and propagated in culture.

We developed a method of propagating pure first trimester human trophoblast cells growing out of primary explants of mechanically derived chorionic villus fragments (Yagel et al, 1989; Graham et al, 1992). We have now extensively characterized these cells during their initial outgrowth and in long-term culture, employing a variety of markers and techniques as outlined below. By double label immunofluorescence using epithelial (cytokeratin) and mesenchymal (vimentin) cell markers, we identified the chorionic villus migrant cell populations as pure trophoblast (39 per cent of outgrowths) or a mixture of trophoblast and fibroblast (61 per cent). Further phenotyping of the pure trophoblast outgrowths by double label immunostaining using anti-cytokeratin antibody and a panel of other primary antisera revealed that these cells exhibit a variety of markers characteristic of extravillous invasive trophoblast cells in situ: insulin-like growth factor (IGF)-II, NDOG-5, proliferating cell nuclear antigen (PCNA), human leucocyte antigen framework antigen (W6/32) and a distinct set of integrins including alpha 1, alpha 3, alpha 5, alpha v and beta 1 subunits and alpha v beta 3/beta 5 vitonectin receptor. They were negative for alpha 6 and beta 4 integrin subunits. Immunogold electron microscopy of explants grown on type IV collagen gel revealed the production of conventional and oncofetal types of fibronectin by mononucleate trophoblast cells and human placental lactogen by multinucleate cells. Immunolabelling, flow cytometry and immunoprecipitation revealed that this phenotypic profile was retained with complete fidelity in the long-term culture; thus, trophoblasts migrating out of first trimester chorionic villus explants and their propagated progeny belong to the invasive extravillous trophoblast of the placenta.

Cell Movement↗
PubMed1975

Radionuclide and angiographic studies of placental circulation in man and rhesus monkey.

Imaging maternal and fetal circulation during perfusion of isolated human placental lobules was performed. Radionuclide and contrast angiograms, specimen scans, and histologic preparations obtained on human material during in vitro investigations were compared to the results obtained in vivo on pregnant rhesus monkeys. The distribution of maternal blood flow within the placenta appeared similar in both human and rhesus studies. The 'spurts' of radiopaque medium shown on the contrast angiograms correlated with the appearance of areas of increased radioactivity. These 'hot spots' are located where the uteroplacental spiral arteries open into the intervillous space or where the perfusion cannulae irrigate the maternal side of the placenta. Time-radioactivity curves reached an early peak and remained the same as did their distribution on delayed scans. The 15 to 30 micron microspheres injected into the intervillous spaces are not removed onto the venous side by maternal flow through arteriovenous communications (or 'shunts') but are retained in localized areas of the intervillous space adjacent to the spiral arteries. Many of these microspheres adhere to the 'brush border' of the chorionic villi syncytiotrophoblast. These comparative studies confirm that rhesus monkeys and perfused human placental lobules are relevant models to investigate uteroplacental hemodynamics.

Animals↗
PubMed2005

The role of ultrasound imaging in diagnosing and investigating early pregnancy failure.

The advent of high-resolution transvaginal ultrasound (TVS) has revolutionized our understanding of the pathophysiology and the management of early pregnancy failure. Knowledge of the ultrasound appearances of normal early pregnancy development and a good understanding of its pitfalls are essential for the diagnosis and management of early pregnancy failure. Ultrasound imaging has rapidly replaced all other techniques used to study normal human development in the first trimester, and ultrasound features of the early gestational sac have corroborated anatomical studies showing that the first structures to appear are the celomic cavity and the secondary yolk sac. No single ultrasound measurement of the different anatomical features in the first trimester has been shown to have a high predictive value for determining early pregnancy outcome. Similarly, Doppler studies have failed to demonstrate abnormal blood flow indices in the first-trimester uteroplacental circulation of pregnancies that subsequently end in miscarriage. Ultrasound parameters combined with maternal serum hormone levels, maternal age, smoking habits, obstetric history and the occurrence of vaginal bleeding have all been combined in multivariate analyses, with mixed results. Combined ultrasound and in-vitro experiments have demonstrated that the maternal circulation inside the placenta starts at the periphery at around 9 weeks of gestation and that this is associated with a physiological oxidative stress which could be the trigger for the formation of the placental membranes. Abnormal development of these membranes can result in subchorionic hemorrhage and threatened miscarriage with subsequent long-term consequences such as preterm rupture of the membranes and preterm labor, irrespective of the finding of a hematoma on ultrasound. In both euploid and aneuploid missed miscarriages there is clear ultrasound evidence for excessive entry of maternal blood at a very early stage inside the developing placenta resulting in oxidative stress and subsequent degeneration of villous tissue. The finding of blood flow in the intervillous space in cases of first-trimester miscarriage using color Doppler also appears to be useful in the prediction of success of expectant management. Miscarriages with blood flow within the intervillous space are up to four times more likely to complete with expectant management. TVS is considered the gold standard in the diagnosis and management of incomplete miscarriage. Expectant management of miscarriage, using ultrasound parameters to determine eligibility, could significantly reduce the number of unnecessary evacuations of the retained products of conception, depending on the criteria used.

Abortion, Incomplete↗
PubMed2000

Evidence that StAR and MLN64 act on the outer mitochondrial membrane as molten globules.

StAR increases the flow of cholesterol from the outer to inner mitochondrial membrane (OMM to IMM), but its mechanism of action remains unclear. MLN64 is a 445 amino acid protein of unknown function that has four N-terminal transmembrane domains and whose C-terminal domain from 218-445 is 37% identical to StAR. N-62 StAR is as active as wild-type StAR, and N-234 MLN64 has 1/3 to 1/2 of StAR's activity. N-62 StAR lacks a mitochondrial leader and is confined to the cytoplasm, indicating that it acts on the OMM. Bacterially expressed N-62 StAR and N-218 MLN64 are active with isolated MA-10 cell mitochondria, indicating the proteins were properly folded. Far-UV CD spectroscopy, unfolding in urea, and fluorescence spectroscopy indicate that StAR undergoes a pH-dependent transition to a molten globule (retained secondary structure, partially lost tertiary structure) and stabilizes in mildly acid conditions. Far-UV CD data indicate that MLN64 undergoes a much less pronounced transition. Western blotting shows that normal human placenta has abundant N-terminally-cleaved 30 kDa MLN64. Partial proteolysis followed by mass spectrometry shows that the C-termini of StAR and MLN64 are sensitive to proteolysis, indicating looser folding. Our model of StAR action is that the protease-resistant domain unfolds slowly during normal mitochondrial entry, keeping StAR in contact with the OMM longer, increasing activity. The transition to the molten globule may be related to interaction with the OMM. These data are consistent with the recent crystallographic structure of N-216 MLN64 in which MLN64 binds cholesterol one molecule at a time, but are not consistent with the suggestion that StAR/MLN64 must reside in the intramembraneous space to transfer cholesterol form the OMM to the IMM.

Animals↗
PubMed1976

Isozyme patterns of glycogen phosphorylase in rat tissues and transplantable hepatomas.

Isozyme patterns of glycogen phosphorylase in the Morris and Yoshida hepatomas were compared electrophoretically and immunochemically with those in rat tissues during development. A 3rd phosphorylase isozyme, observed previously in hepatomas and fetal tissues by isoelectric focusing and by immunochemical titration, was also separated by polyacrylamide disc gel electrophoresis. It was observed commonly in various rat hepatomas, together with variable activities of the liver type, depending on the degree of differentiation. This isozyme is nearly the sole type in placenta and early embryo, and in liver and skeletal muscle it is replaced during fetal development with the organ-specific liver and muscle type. In adult rat brain the fetal type is retained at low levels, together with the muscle type. In kidney, spleen, testis, uterus, lung, and stomach, the fetal type is present together with the liver type. This isozyme in hepatomas and adult brain is identical with the fetal-type, as determined by Ouchterlony double diffusion and activity inhibition tests. Thus, it is considered to be a prototype whose appearance in hepatomas is one of many known examples of fetal protein expression in cancer. In some poorly differentiated hepatomas, the liver-type isozyme migrated slightly more slowly in polyacrylamide gel but could not be distinguished from the liver isozyme immunochemically.

Animals↗