Showing papers by "Fuller W. Bazer published in 2003"
TL;DR: This minireview summarizes information regarding uterine and placental expression of OPN that has accumulated over the past 15 yr, and structural/functional properties of this protein that are likely relevant to its role(s) during pregnancy are described.
Abstract: Osteopontin (OPN) is an acidic member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family of extracellular matrix proteins/cytokines that undergoes extensive posttranslational modification, including phosphorylation, glycosylation, and cleavage, yielding molecular mass variants ranging in size from 25 to 75 kDa. The result is a versatile protein(s) with multiple functions arising from its role as a mediator of cell-cell and cell-extracellular matrix (ECM) communication that encompass both normal and tumorigenic developmental processes, immunological responses during inflammation and wound healing, and biomineralization. Studies in primates, pigs, sheep, and rodents have revealed that OPN is a major constituent of the uterine-placental microenvironment with influence as 1) a component of histotroph required for adhesion and signal transduction at the uterine-placental interface throughout pregnancy, 2) a gene product expressed by uterine stroma contributing to a decidualization-like transformation that correlates with the degree of conceptus invasiveness, and 3) a product of resident uterine and placental immune cells that may regulate their behavior and cytokine production. This minireview summarizes information regarding uterine and placental expression of OPN that has accumulated over the past 15 yr, and we briefly describe structural/functional properties of this protein that are likely relevant to its role(s) during pregnancy. Comparative studies have offered insights into the potential hormonal/cytokine, cellular, and molecular mechanisms underlying OPN-mediated adhesion, remodeling, and cell-cell/cell-ECM communication within the uterus and placenta. OPN has the potential to profoundly impact pregnancy, and investigators are now challenged to focus on the mechanistic nature of the functions of this multifaceted and major component of the uterine-placental microenvironment.
302 citations
TL;DR: The hypothesis that arginine is also the most abundant amino acid in ovine allantoic fluid is tested to test and novel findings of the unusual abundance of traditionally classified nonessential amino acids in allantoi fluid raise important questions regarding their roles in Ovine conceptus development are raised.
Abstract: We recently reported an unusual abundance of arginine (4-6 mM) in porcine allantoic fluid during early gestation. However, it is not known whether such high concentrations of arginine are unique for porcine allantoic fluid or whether they represent an important physiological phenomenon for mammals. The present study was conducted to test the hypothesis that arginine is also the most abundant amino acid in ovine allantoic fluid. Allantoic and amniotic fluids, as well as fetal and maternal plasma samples, were obtained from ewes between Days 30 and 140 of gestation. Glycine was the most abundant amino acid in maternal uterine arterial plasma, representing approximately 25% of total alpha-amino acids. Alanine, glutamine, glycine, plus serine contributed approximately 50% of total alpha-amino acids in fetal plasma. Fetal:maternal plasma ratios for amino acids varied greatly, being less than 1 for glutamate during late gestation, 1.5-3 for most amino acids throughout gestation, and greater than 10 for serine during late gestation. Marked changes were observed in amino acid concentrations in amniotic and allantoic fluids associated with conceptus development. Concentrations of alanine, citrulline, and glutamine in allantoic fluid increased by 20-, 34-, and 18-fold, respectively, between Days 30 and 60 of gestation and were 24.7, 9.7, and 23.5 mM, respectively, on Day 60 of gestation (compared with 0.8 mM arginine). Remarkably, alanine, citrulline, plus glutamine accounted for approximately 80% of total alpha-amino acids in allantoic fluid during early gestation. Serine (16.5 mM) contributed approximately 60% of total alpha-amino acids in allantoic fluid on Day 140 of gestation. These novel findings of the unusual abundance of traditionally classified nonessential amino acids in allantoic fluid raise important questions regarding their roles in ovine conceptus development.
139 citations
TL;DR: Results of the present study indicate metabolic coordination among the several integrated pathways that support high rates of polyamine synthesis in the placenta and endometrium during early pregnancy.
Abstract: Polyamines (putrescine, spermidine, and spermine) are essential for placental growth and angiogenesis. However, little is known about changes in polyamine synthesis associated with development of the ovine conceptus (embryo/fetus and associated placental membranes). We hypothesized that rates of placental polyamine synthesis were maximal during the rapid placental growth that occurs in the first half of pregnancy. This hypothesis was tested using ewes between Days 30 and 140 of gestation. Columbia cross-bred ewes were hysterectomized on Days 30, 40, 60, 80, 100, 120, or 140 of gestation (Day 0 5 mating; n 5 4 ewes/day) to obtain placentomes, intercotyledonary placenta, intercaruncular endometrium, and allantoic as well as amniotic fluids. The tissues were analyzed for ornithine decarboxylase (ODC) and arginase activities; arginine, ornithine, and polyamine concentrations; and polyamine synthesis using radiochemical and chromatographic methods. Maximal ODC and arginase activities and the highest rates of polyamine synthesis were observed in all tissues on Day 40 of gestation. Concentrations of ornithine and polyamines in placentomes and intercaruncular endometrium also peaked on Day 40 of gestation. In ovine allantoic and amniotic fluids, polyamines were most abundant during early (Days 40‐60) and late (Days 100‐ 140) gestation, respectively. Amniotic fluid spermine increased progressively with advancing gestation. Results of the present study indicate metabolic coordination among the several integrated pathways that support high rates of polyamine synthesis in the placenta and endometrium during early pregnancy. Our findings may have important implications for both intrauterine growth retardation and fetal origins of diseases in adults. developmental biology, placenta, pregnancy, uterus
101 citations
TL;DR: IFNtau does regulate genes independent of STAT1 in the endometrial LE and U3A cells and dependent on STAT1 on the endometricrial stroma and 2fTGH cells, which may be important in establishment of uterine receptivity to the embryo and conceptus implantation.
Abstract: Interferon τ (IFNτ), a type I IFN produced by the conceptus trophectoderm, increases many type I IFN-stimulated genes (ISGs) in the ovine uterine endometrial stroma and glandular epithelium (GE) using signal transducer and activator of transcription 1 (STAT1)-dependent pathways. Most ISGs are not induced or increased by IFNτ in the STAT1-negative endometrial luminal epithelium (LE). The objective was to identify genes regulated by IFNτ in a STAT1-independent manner using DNA microarray and human cell lines. The RNA from human 2fTGH and U3A (STAT1 null 2fTGH) cell lines, stimulated for 24 h with nothing or recombinant ovine IFNτ, was profiled using an Affymetrix human genome U95Av2 microarray. In 2fTGH cells, IFNτ increased the expression of 101 genes at least 2-fold, including IFN-inducible 56-kDa protein (IFI56), ISG12 or p27, and guanylate binding protein isoform I (GBP-2). In U3A cells, IFNτ increased expression of 66 genes at least 2-fold, including Wnt7a. Steady-state levels of IFI56, ISG12, GBP-2, a...
96 citations
TL;DR: The silencing of MHC class I α chain and β2MG genes in the endometrial LE and sGE during pregnancy recognition and establishment may be a critical mechanism preventing immune rejection of the conceptus allograft.
Abstract: Major histocompatibility complex (MHC) class I molecules, consisting of an a chain and b2-microglobulin (b2MG), play an important role in immune rejection responses by discriminating self and nonself and are increased by type I interferons during antiviral responses. Interferon tau (IFNt), the pregnancy-recognition signal in ruminants, is a type I interferon produced by the ovine conceptus between Days 11 and 21 of gestation. In study 1, expression of MHC class I a chain and b2MG mRNA and protein was detected primarily in endometrial luminal epithelium (LE) and glandular epithelium (GE) on Days 10 and 12 of the estrous cycle and pregnancy. On Days 14‐20 of pregnancy, MHC class I and b2MG expression increased only in endometrial stroma and GE and, concurrently, was absent in LE and superficial ductal GE (sGE). Although neither MHC class I nor b2MG proteins were detected in Day 20 trophectoderm, b2MG mRNA was detected in conceptus trophectoderm. In study 2, cyclic ewes were ovariectomized on Day 5, treated daily with progesterone to Day 16, received intrauterine infusions between Days 11 and 16 of either control serum proteins or recombinant ovine IFNt, and were hysterectomized on Day 17. The IFNt increased MHC class I and b2MG expression only in endometrial stroma and GE. During pregnancy, MHC class I and b2MG gene expression is inhibited in endometrial LE and sGE but, paradoxically, is stimulated by IFNt in the stroma and GE. The silencing of MHC class I a chain and b2MG genes in the endometrial LE and sGE during pregnancy recognition and establishment may be a critical mechanism preventing immune rejection of the conceptus allograft. b2-microglobulin, interferon, major histocompatibility complex, ovine, uterus
85 citations
TL;DR: Measurements of changes in the decidualization marker genes OPN, desmin, and alpha smooth muscle actin in ovine and porcine uterine stroma throughout pregnancy suggest that uterineStromal decidUALization is common to species with different types of placentation, but the extent is variable and correlates with the depth of trophoblast invasion during implantation.
Abstract: Osteopontin (OPN) is a component of the extracellular matrix that interacts with cell surface receptors, including integrins, to mediate cell adhesion, migration, differentiation, survival, and immune function. In pregnant mice and primates, OPN has been detected in decidualized stroma and is considered to be a gene marker for decidualization. Decidualization involves transformation of spindle-like fibroblasts into polygonal epithelial-like cells that are hypothesized to limit conceptus trophoblast invasion through the uterine wall during invasive implantation. Decidualization is not considered characteristic of species with noninvasive implantation, such as domestic animals. However, the extent of trophoblast invasion between sheep and pigs differs, with sheep exhibiting erosion of the uterine luminal epithelium (LE) and fusion of trophectoderm with LE to form syncytia, and pigs maintaining an intact LE throughout pregnancy. Therefore, the present study measured changes in the decidualization marker genes OPN, desmin, and alpha smooth muscle actin (alphaSMA) in ovine and porcine uterine stroma throughout pregnancy. The morphology of endometrial stromal cells in pregnant ewes changes following conceptus attachment, with cells increasing in size and becoming polyhedral in shape by Day 35 of pregnancy. Expression of OPN mRNA and protein, as well as desmin and alphaSMA proteins, was observed in this same uterine stromal compartment. In contrast, no morphological changes in uterine stroma nor induction of OPN mRNA and protein, or desmin protein, were detected during porcine pregnancy. Interestingly, alphaSMA protein was absent on Day 20, but prominent in uterine stroma of pregnant pigs on Day 45. Collectively, these results indicate that the uterine stroma of sheep undergoes a program of differentiation similar to decidualization in invasive implanting species, whereas porcine stroma exhibits differentiation that is more limited than that in sheep, rodents, or primates. Results suggest that uterine stromal decidualization is common to species with different types of placentation, but the extent is variable and correlates with the depth of trophoblast invasion during implantation.
82 citations
TL;DR: expression of COX-2 in the endometrial epithelia as well as conceptus is likely to have a beneficial regulatory role in implantation and development of the conceptus and antiluteolytic effects of IFNτ are to inhibit ERα and OTR gene transcription, thereby preventing endometrian production of luteolysis pulses of PGF.
Abstract: In sheep, the uterus produces luteolytic pulses of prostaglandin F2α (PGF) on Days 15 to 16 of estrous cycle to regress the corpus luteum (CL). These PGF pulses are produced by the endometrial lumenal epithelium (LE) and superficial ductal glandular epithelium (sGE) in response to binding of pituitary and/or luteal oxytocin to oxytocin receptors (OTR) and liberation of arachidonic acid, the precursor of PGF. Cyclooxygenase-one (COX-1) and COX-2 are rate-limiting enzymes in PGF synthesis, and COX-2 is the major form expressed in ovine endometrium. During pregnancy recognition, interferon tau (IFNτ), produced by the conceptus trophectoderm, acts in a paracrine manner to suppress development of the endometrial epithelial luteolytic mechanism by inhibiting transcription of estrogen receptor α (ERα) (directly) and OTR (indirectly) genes. Conflicting studies indicate that IFNτ increases, decreases or has no effect on COX-2 expression in bovine and ovine endometrial cells. In Study One, COX-2 mRNA and protein were detected solely in endometrial LE and sGE of both cyclic and pregnant ewes. During the estrous cycle, COX-2 expression increased from Days 10 to 12 and then decreased to Day 16. During early pregnancy, COX-2 expression increased from Days 10 to 12 and remained higher than in cyclic ewes. In Study Two, intrauterine infusion of recombinant ovine IFNτ in cyclic ewes from Days 11 to 16 post-estrus did not affect COX-2 expression in the endometrial epithelium. These results clearly indicate that IFNτ has no effect on expression of the COX-2 gene in the ovine endometrium. Therefore, antiluteolytic effects of IFNτ are to inhibit ERα and OTR gene transcription, thereby preventing endometrial production of luteolytic pulses of PGF. Indeed, expression of COX-2 in the endometrial epithelia as well as conceptus is likely to have a beneficial regulatory role in implantation and development of the conceptus.
77 citations
TL;DR: The hypothesis that ovine OPN is a component of histotroph secreted by the uterine GE that accumulates at the uterus-placental interface to influence maternal-fetal interactions throughout gestation in sheep is supported.
Abstract: Osteopontin (OPN) is a phosphorylated and glycosylated, secreted protein that is present in various epithelial cells and biological fluids. On freezing and thawing or treatment with proteases, the native 70-kDa protein gives rise to 45- and 24-kDa fragments. Secreted OPN functions as an extracellular matrix (ECM) protein that binds cell surface receptors to mediate cell-cell adhesion, cell-ECM communication, and cell migration. In sheep and humans, OPN is proposed to be a secretory product of uterine glandular epithelium (GE) that binds to uterine luminal epithelium (LE) and conceptus trophectoderm to mediate conceptus attachment, which is essential to maintain pregnancy through the peri-implantation period. Cell-cell adhesion, communication, and migration likely are important at the interface between uterus and placenta throughout pregnancy, but to our knowledge, endometrial and/or placental expression of OPN beyond the peri-implantation period has not been documented in sheep. Therefore, the present study determined temporal and spatial alterations in OPN mRNA and protein expression in the ovine uterus between Days 25 and 120 of pregnancy. The OPN mRNA in total ovine endometrium increased 30-fold between Days 40 and 80 of gestation. In situ hybridization and immunofluorescence analyses revealed that the predominant source of OPN mRNA and protein throughout pregnancy was the uterine GE. Interestingly, the 45-kDa form of OPN was detected exclusively, continuously, and abundantly along the apical surface of LE, on conceptus trophectoderm, and along the uterine-placental interface of both interplacentomal and placentomal regions through Day 120 of pregnancy. The 45-kDa OPN is a proteolytic cleavage fragment of the native 70-kDa OPN, and it is the most abundant form in uterine flushes during early pregnancy. The 45-kDa OPN is more stimulatory to cell attachment and cell migration than the native 70-kDa protein. Collectively, the present results support the hypothesis that ovine OPN is a component of histotroph secreted by the uterine GE that accumulates at the uterine-placental interface to influence maternal-fetal interactions throughout gestation in sheep.
72 citations
TL;DR: Results indicate that oPL binds to receptors in the endometrial glands and that oPRL is more effective than oGH in competing for these binding sites, and effects of oPL on the endometricrial glands may be mediated by receptors for o PRLR and oGH.
Abstract: A hormonal servomechanism has been proposed to regulate differentiation and function of the endometrial glandular epithelium (GE) in the ovine uterus during pregnancy. This mechanism involves sequential actions of estrogen, progesterone, ovine interferon tau (IFNtau), placental lactogen (oPL), and placental growth hormone (oGH). The biological actions of oPL in vitro are mediated by homodimerization of the prolactin receptor (oPRLR) and heterodimerization of the oPRLR and oGH receptor. The objectives of the study were to determine the effects of intrauterine oPL, oGH, and their combination on endometrial histoarchitecture and gene expression and to localize and characterize binding sites for oPL in the ovine uterus in vivo using an in situ ligand binding assay. Intrauterine infusion of oPL and/or oGH following IFNtau into ovariectomized ewes treated with progesterone daily differentially affected endometrial gland number and expression of uterine milk proteins and osteopontin. However, neither hormone affected PRLR, insulin-like growth factor (IGF)-I, or IGF-II mRNA levels in the endometrium. A chimeric protein of placental secretory alkaline phosphatase (SEAP) and oPL was used to identify and characterize binding sites for oPL in frozen sections of interplacentomal endometrium from pregnant ewes. Specific binding of SEAP-oPL was detected in the endometrial GE on Days 30, 60, 90, and 120 of pregnancy. In Day 90 endometrium, SEAP-oPL binding to the endometrial GE was displaced completely by oPL and prolactin (oPRL) but only partially by oGH. Binding experiments using the extracellular domain of the oPRLR also showed that iodinated oPL binding sites could be competed for by oPRL and oPL but not by oGH. Collectively, results indicate that oPL binds to receptors in the endometrial glands and that oPRL is more effective than oGH in competing for these binding sites. Thus, effects of oPL on the endometrial glands may be mediated by receptors for oPRL and oGH.
67 citations
TL;DR: Results indicate that PRL regulates endometrial adenogenesis in the neonatal ovine uterus.
Abstract: Uterine gland development or adenogenesis in the neonatal ovine uterus involves budding, proliferation, and branching morphogenesis of the glandular epithelium (GE) from the luminal epithelium (LE) between birth (postnatal day or PND 0) and PND 56. This critical developmental event is coincident with increases in serum PRL and expression of long and short PRL receptors specifically in the nascent and proliferating GE. In study one, ewes were treated with a placebo pellet as a control (CX) or a bromocryptine mesylate pellet from PNDs 0-56. On PND 56, the endometrium of bromocryptine mesylate ewes contained fewer glands, particularly in the stratum spongiosum that contained numerous coiled and branched glands in CX uteri. In study two, ewes were treated with saline as a CX or recombinant ovine PRL from PNDs 0-56. Treatment with PRL increased gland number and density on PND 14 and PND 56. In study three, expression of signal transducers and activators of transcription (STAT) 1, 3, and 5 proteins was detected in the developing glands from PNDs 7-56. In study four, Western blot analyses indicated that PRL increased levels of phosphorylated STATs 1 and 5, but not STAT 3, and phosphorylated ERK 1 and 2 MAPKs and c-Jun N-terminal kinase/stress-activated protein kinase proteins in explanted PND 28 ovine uteri. Collectively, results indicate that PRL regulates endometrial adenogenesis in the neonatal ovine uterus.
28 citations
TL;DR: Because OvLVΔdu-egfp is attenuated for pathogenicity in vitro, replicates in vivo and stimulates an antibody response, subsequent experiments need to address the likelihood of using OvLV/egfp as an attenuated, live-virus vaccine to protect sheep against OvLV-induced disease when challenged with pathogenic OvLV.
Abstract: A dUTPase gene (du) deleted ovine lentivirus (OvLVΔdu) mutant, derived from Visna/maedi virus (VMV) molecular clone KV1772, was constructed. Subsequently, a copy of the optimized green fluorescent protein (egfp) coding region was fused into the viral pol open reading frame (ORF) at the deleted du locus to generate viral mutant, OvLVΔdu-egfp. OvLVΔdu reverse transcriptase (RT) activity and titer of infectious virus in goat synovial membrane (GSM) cell cultures were not affected compared to that of KV1772 and OvLV-85/34 strain (p < 0.05). By contrast, OvLVΔdu-egfp RT activity and virus titer were lower than for KV1772 and OvLVΔdu (p < 0.05). OvLV-85/34 RT in sheep monocyte-derived macrophages (SMDM) was higher than that of KV1772, OvLVΔdu and OvLVΔdu-egfp (p < 0.05). The ability to prevent dUTP mis-incorporation into newly synthesized DNA was disrupted in OvLVΔdu and OvLVΔdu-egfp (p < 0.05). Immunoprecipitation demonstrated that GFP is expressed by OvLVΔdu-egfp at a low level. OvLVΔdu-egfp retained egfp after 10 passages in cell culture.
TL;DR: Although most 'top ranked' traditional journals now offer web access to recent publications, and to less or more of their archives, not everyone has the luxury of access through their university, or has his/her subscription paid for, or can afford to pay US $30–35 for an electronic reprint.
Abstract: Electronic journals are the basis of a world of purely electronic scientific communication. Just imagine, no more bookshelves and mountains of disorganized paperwork, no more late nights organizing and searching for articles of interest. For most active research-oriented students and scientists this is already a reality, or will be in the near future.
Although most 'top ranked' traditional journals now offer web access to recent publications, and to less or more of their archives, not everyone has the luxury of access through their university, or has his/her subscription paid for, or can afford to pay US $30–35 for an electronic reprint. Traditionally, journals generated their revenue from individual subscribers, private and/or state owned institutions, page charges from authors, and charges for color illustrations. Consequently, the traditional science publishing industry limited access to scientific publications to scientists in the developed countries while, in many cases, leaving the rest of the world unattended.
Patent•
12 Jun 2003TL;DR: In this article, the present invention is generally directed to improving fertility in mammals by administering at least one lactogenic or somatogenic hormone to a mammal in order to increase reproductive efficiency.
Abstract: The present invention is generally directed to improving fertility in mammals. Methods of the present invention include increasing reproductive efficiency in mammals by administering at least one lactogenic or somatogenic hormone to a mammal in order to increase reproductive efficiency (Figure 1). Additional methods of the present invention include increasing endometrial adenogenesis in a mammal.