Secreted phosphoprotein 1 (SPP1, osteopontin) binds to integrin alpha v beta 6 on porcine trophectoderm cells and integrin alpha v beta 3 on uterine luminal epithelial cells, and promotes trophectoderm cell adhesion and migration

Glomerular endothelial cell heterogeneity in Alport syndrome

Glomerular endothelial cells (GEC) are a crucial component of the glomerular physiology and their damage contributes to the progression of chronic kidney diseases. How GEC affect the pathology of Alport syndrome (AS) however, is unclear. We characterized GEC from wild type (WT) and col4α5 knockout AS mice, a hereditary disorder characterized by progressive renal failure. We used endothelial-specific Tek-tdTomato reporter mice to isolate GEC by FACS and performed transcriptome analysis on them from WT and AS mice, followed by in vitro functional assays and confocal and intravital imaging studies. Biopsies from patients with chronic kidney disease, including AS were compared with our findings in mice. We identified two subpopulations of GEC (dim^tdT and bright^tdT) based on the fluorescence intensity of the Tek^tdT signal. In AS mice, the bright^tdT cell number increased and presented differential expression of endothelial markers compared to WT. RNA-seq analysis revealed differences in the immune and metabolic signaling pathways. In AS mice, dim^tdT and bright^tdT cells had different expression profiles of matrix-associated genes (Svep1, Itgβ6), metabolic activity (Apom, Pgc1α) and immune modulation (Apelin, Icam1) compared to WT mice. We confirmed a new pro-inflammatory role of Apelin in AS mice and in cultured human GEC. Gene modulations were identified comparable to the biopsies from patients with AS and focal segmental glomerulosclerosis, possibly indicating that the same mechanisms apply to humans. We report the presence of two GEC subpopulations that differ between AS and healthy mice or humans. This finding paves the way to a better understanding of the pathogenic role of GEC in AS progression and could lead to novel therapeutic targets.

Embryo gene expression in pig pregnancy

Pregnancy is a complex process in which significant changes occur continually in both the corpora lutea and in the endometrium of the females and varies depending on the embryonic, pre-implantation or foetal stages. In the embryonic stages, the majority of genes expressed in the pig embryo correspond to the loss of cellular pluripotency. In contrast, the implantation consists of three phases: elongation of the conceptus, adhesion and union of the embryo to the endometrial epithelium. During these phases, many factors are expressed, including growth factors, molecules that facilitate adhesion and cytokines. All these changes are ultimately regulated by different lipid and hormonal substances, specifically by progesterone, oestradiol and prostaglandins, which regulate the expression of many proteins necessary for the development of the embryo, endometrial remodelling and embryo-maternal communication. This paper is a review of primary gene regulatory mechanisms in pigs during different stages of implantation.

The role of Galectin-1 in HIV associated preeclampsia

OBJECTIVE

In this study, the role of Gal1, a regulatory protein involved in receptor binding and gene transcription within trophoblast cells, in the pathophysiology of HIV associated preeclampsia was determined by immunolocalizing its expression in the placenta of a South African cohort.

STUDY DESIGN

this is an analytical study carried out at the Optics and Imaging Center, Neslon R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa. A hundred and twenty HIV negative or positive, Black African primigrad or multigravid women with pre-eclamptic and normotensive pregnancies were involved in the study. Post-delivery, full thickness of centrally located placental tissue obtained was fixed for immunohistochemistry. The expression of Gal1 was immunolocalized using immunohistochemical assay kit and further quantified with using AxioVision Image analysis software package. Student t-test was used to compare the levels of the analytes while One-way ANOVA was used for comparison across the groups.

RESULTS

Gal1 immunoreactivity was observed within the Hofbauer cells, cytotrophoblast, syncytial knots and in the endothelial cells lining blood vessels in both exchange and conducting villi of both normotensive and preeclamptic pregnancies regardless of HIV status. There was a down regulation in Gal1 immunoreactivity in both the exchange and conducting villi of preeclamptic compared to normotensive pregnancies. However, there was no significant effect of HIV infection on Gal1 immunostaining in both villi types.

CONCLUSION

The down regulation of Gal1 in preeclampsia may be due to the inhibition of the MAPK pathway. Since Gal1 influences differentiation and migration, the defective trophoblast invasion in preeclampsia may emanate from its decreased immunoexpression. This highlights the role of Gal1 in angiogenesis and placentation.

Adhesion molecules in gamete transport, fertilization, early embryonic development, and implantation-role in establishing a pregnancy in cattle: A review

Cell-cell adhesion molecules have critically important roles in the early events of reproduction including gamete transport, sperm-oocyte interaction, embryonic development, and implantation. Major adhesion molecules involved in reproduction include cadherins, integrins, and disintegrin and metalloprotease domain-containing (ADAM) proteins. ADAMs on the surface of sperm adhere to integrins on the oocyte in the initial stages of sperm-oocyte interaction and fusion. Cadherins act in early embryos to organize the inner cell mass and trophectoderm. The trophoblast and uterine endometrial epithelium variously express cadherins, integrins, trophinin, and selectin, which achieve apposition and attachment between the elongating conceptus and uterine epithelium before implantation. An overview of the major cell-cell adhesion molecules is presented and this is followed by examples of how adhesion molecules help shape early reproductive events. The argument is made that a deeper understanding of adhesion molecules and reproduction will inform new strategies that improve embryo survival and increase the efficiency of natural mating and assisted breeding in cattle.

Spatial organization of endometrial gene expression at the onset of embryo attachment in pigs

BACKGROUND

During the preimplantation phase in the pig, the conceptus trophoblast elongates into a filamentous form and secretes estrogens, interleukin 1 beta 2, interferons, and other signaling molecules before attaching to the uterine epithelium. The processes in the uterine endometrium in response to conceptus signaling are complex. Thus, the objective of this study was to characterize transcriptome changes in porcine endometrium during the time of conceptus attachment considering the specific localization in different endometrial cell types.

RESULTS

Low-input RNA-sequencing was conducted for the main endometrial compartments, luminal epithelium (LE), glandular epithelium (GE), blood vessels (BV), and stroma. Samples were isolated from endometria collected on Day 14 of pregnancy and the estrous cycle (each group n = 4) by laser capture microdissection. The expression of 12,000, 11,903, 11,094, and 11,933 genes was detectable in LE, GE, BV, and stroma, respectively. Differential expression analysis was performed between the pregnant and cyclic group for each cell type as well as for a corresponding dataset for complete endometrium tissue samples. The highest number of differentially expressed genes (DEGs) was found for LE (1410) compared to GE, BV, and stroma (800, 1216, and 384). For the complete tissue, 3262 DEGs were obtained. The DEGs were assigned to Gene Ontology (GO) terms to find overrepresented functional categories and pathways specific for the individual endometrial compartments. GO classification revealed that DEGs in LE were involved in 'biosynthetic processes', 'related to ion transport', and 'apoptotic processes', whereas 'cell migration', 'cell growth', 'signaling', and 'metabolic/biosynthetic processes' categories were enriched for GE. For blood vessels, categories such as 'focal adhesion', 'actin cytoskeleton', 'cell junction', 'cell differentiation and development' were found as overrepresented, while for stromal samples, most DEGs were assigned to 'extracellular matrix', 'gap junction', and 'ER to Golgi vesicles'.

CONCLUSIONS

The localization of differential gene expression to different endometrial cell types provided a significantly improved view on the regulation of biological processes involved in conceptus implantation, such as the control of uterine fluid secretion, trophoblast attachment, growth regulation by Wnt signaling and other signaling pathways, as well as the modulation of the maternal immune system.

Gene Expression Profiling of the Extracellular Matrix Signature in Macrophages of Different Activation Status: Relevance for Skin Wound Healing

The extracellular matrix (ECM) provides structural support for tissue architecture and is a major effector of cell behavior during skin repair and inflammation. Macrophages are involved in all stages of skin repair but only limited knowledge exists about macrophage-specific expression and regulation of ECM components. In this study, we used transcriptome profiling and bioinformatic analysis to define the unique expression of ECM-associated genes in cultured macrophages. Characterization of the matrisome revealed that most genes were constitutively expressed and that several genes were uniquely regulated upon interferon gamma (IFNγ) and dexamethasone stimulation. Among those core matrisome and matrisome-associated components transforming growth factor beta (TGFβ)-induced, matrix metalloproteinase 9 (MMP9), elastin microfibril interfacer (EMILIN)-1, netrin-1 and gliomedin were also present within the wound bed at time points that are characterized by profound macrophage infiltration. Hence, macrophages are a source of ECM components in vitro as well as during skin wound healing, and identification of these matrisome components is a first step to understand the role and therapeutic value of ECM components in macrophages and during wound healing.

Association of foetal size and sex with porcine foeto-maternal interface integrin expression

Integrins regulate adhesion at the foeto-maternal interface by interacting with secreted phosphoprotein 1 (SPP1) and fibronectin (FN). It is hypothesised that impaired foetal growth of ‘runt’ piglets is linked to altered integrin signalling at the foeto-maternal interface. Placental and endometrial samples associated with the lightest and closest to mean litter weight (CTMLW) (gestational day (GD18, 30, 45, 60 and 90), of both sex (GD30, 45, 60 and 90) (n = 5–8 litters/GD), Large White × Landrace conceptuses or foetuses were obtained. The mRNA expression of the integrin subunits (ITG) ITGA2, ITGAV, ITGB1, ITGB3, ITGB5, ITGB6, ITGB8, SPP1 and FN was quantified by qPCR. Temporal changes in mRNA expression were observed, with different profiles in the two tissues. Endometrial ITGB1 (P ≤ 0.05, GD45) and SPP1 (P ≤ 0.05, all GD combined and GD60) expression was decreased in samples supplying the lightest compared to the CTMLW foetuses. Placentas supplying female foetuses had decreased expression of ITGB6 (GD45, P ≤ 0.05) and FN (GD90, P ≤ 0.05) compared to those supplying male foetuses. Endometrial samples supplying females had increased ITGB3 (P ≤ 0.05, GD60) and FN (P ≤ 0.05, GD30) expression and decreased SPP1 (P ≤ 0.05, GD60) expression compared to male foetuses. Correlations between mean within-gilt mRNA expression and percentage prenatal survival, number of live foetuses or conceptuses and percentage male foetuses were observed. This study has highlighted novel and dynamic associations between foetal size, sex and integrin subunit mRNA expression at the porcine foeto-maternal interface. Further studies should be performed to improve the understanding of the mechanisms behind these novel findings.

The cancer-related transcription factor RUNX2 modulates expression and secretion of the matricellular protein osteopontin in osteosarcoma cells to promote adhesion to endothelial pulmonary cells and lung metastasis

Osteosarcomas are bone tumors that frequently metastasize to the lung. Aberrant expression of the transcription factor, runt-related transcription factor 2 (RUNX2), is a key pathological feature in osteosarcoma and associated with loss of p53 and miR-34 expression. Elevated RUNX2 may transcriptionally activate genes mediating tumor progression and metastasis, including the RUNX2 target gene osteopontin (OPN/SPP1). This gene encodes a secreted matricellular protein produced by osteoblasts to regulate bone matrix remodeling and tissue calcification. Here we investigated whether and how the RUNX2/OPN axis regulates lung metastasis of osteosarcoma. Importantly, RUNX2 depletion attenuates lung metastasis of osteosarcoma cells in vivo. Using next-generation RNA-sequencing, protein-based assays, as well as the loss- and gain-of-function approaches in selected osteosarcoma cell lines, we show that osteopontin messenger RNA levels closely correlate with RUNX2 expression and that RUNX2 controls the levels of secreted osteopontin. Elevated osteopontin levels promote heterotypic cell-cell adhesion of osteosarcoma cells to human pulmonary microvascular endothelial cells, but not in the presence of neutralizing antibodies. Collectively, these findings indicate that the RUNX2/OPN axis regulates the ability of osteosarcoma cells to attach to pulmonary endothelial cells as a key step in metastasis of osteosarcoma cells to the lung.

Mechanisms for the establishment and maintenance of pregnancy: synergies from scientific collaborations

Research on the functions of interferon tau (IFNT) led to the theory of pregnancy recognition signaling in ruminant species. But IFNT does much more as it induces expression of interferon regulatory factor 2 (IRF2) in uterine luminal (LE), superficial glandular (sGE), but not glandular (GE) epithelia. First, IRF2 silences transcription of the estrogen receptor alpha gene and, indirectly, transcription of the oxytocin receptor gene to abrogate development of the luteolytic mechanism to prevent regression of the corpus luteum and its production of progesterone for establishing and maintaining pregnancy. Second, IRF2 silences expression of classical interferon-stimulated genes in uterine LE and sGE; however, uterine LE and sGE respond to progesterone (P4) and IFNT to increase expression of genes for transport of nutrients into the uterine lumen such as amino acids and glucose. Other genes expressed by uterine LE and sGE encode for adhesion molecules such as galectin 15, cathepsins, and cystatins for tissue remodeling, and hypoxia-inducible factor relevant to angiogenesis and survival of blastocysts in a hypoxic environment. IFNT is also key to a servomechanism that allows uterine epithelia, particularly GE, to proliferate and to express genes in response to placental lactogen and placental growth hormone in sheep. The roles of secreted phosphoprotein 1 are also discussed regarding its role in implantation in sheep and pigs, as well as its stimulation of expression of mechanistic target of rapamycin mRNA and protein which is central to proliferation, migration, and gene expression in the trophectoderm cells.

Endometrial response to conceptus-derived estrogen and interleukin-1β at the time of implantation in pigs

The establishment of pregnancy is a complex process that requires a well-coordinated interaction between the implanting conceptus and the maternal uterus. In pigs, the conceptus undergoes dramatic morphological and functional changes at the time of implantation and introduces various factors, including estrogens and cytokines, interleukin-1β2 (IL1B2), interferon-γ (IFNG), and IFN-δ (IFND), into the uterine lumen. In response to ovarian steroid hormones and conceptus-derived factors, the uterine endometrium becomes receptive to the implanting conceptus by changing its expression of cell adhesion molecules, secretory activity, and immune response. Conceptus-derived estrogens act as a signal for maternal recognition of pregnancy by changing the direction of prostaglandin (PG) F_2α from the uterine vasculature to the uterine lumen. Estrogens also induce the expression of many endometrial genes, including genes related to growth factors, the synthesis and transport of PGs, and immunity. IL1B2, a pro-inflammatory cytokine, is produced by the elongating conceptus. The direct effect of IL1B2 on endometrial function is not fully understood. IL1B activates the expression of endometrial genes, including the genes involved in IL1B signaling and PG synthesis and transport. In addition, estrogen or IL1B stimulates endometrial expression of IFN signaling molecules, suggesting that estrogen and IL1B act cooperatively in priming the endometrial function of conceptus-produced IFNG and IFND that, in turn, modulate endometrial immune response during early pregnancy. This review addresses information about maternal-conceptus interactions with respect to endometrial gene expression in response to conceptus-derived factors, focusing on the roles of estrogen and IL1B during early pregnancy in pigs.

Alterations in the distribution of actin and its binding proteins in the porcine endometrium during early pregnancy: Possible role in epithelial remodeling and embryo adhesion

During early pregnancy, uterine epithelial cells undergo major transformations in their cytoskeleton that make the endometrium receptive for conceptus attachment. Actin binding proteins (ABPs) such as cofilin, gelsolin, and vinculin are involved in regulating actin polymerization, severing or crosslinking actin to integrins. However, whether ABPs are involved in epithelial remodeling or embryo adhesion in pigs is unknown. Therefore, the expression and distribution of these proteins were investigated in porcine endometrium on Days 10 and 13 (pre-implantation period), and 16 (attachment phase) of the estrous cycle or pregnancy. While day and pregnancy status had no effect on ABP gene expression, the protein abundance of vinculin was significantly higher on Day 13 than on Day 10 (p < 0.05) of the estrous cycle, and its abundance was highest on Day 16 in the pregnant endometrium. Immunofluorescent staining showed alterations in the distribution of these proteins depending on the day of the estrous cycle or early pregnancy examined. Double immunofluorescent staining for the ABPs and actin revealed that while cofilin co-localized with actin in the apical epithelium on Days 13 and 16 of the estrous cycle, in pregnant animals, it was strongly associated with actin in the sub-epithelial stroma of the endometrium. Gelsolin was also co-localized with actin in the apical epithelium on Days 13 and 16 of the estrous cycle, but this association was absent in the pregnant endometrium. Vinculin co-localized with actin in the sub-epithelial stroma on Days 13 and 16 irrespective of the reproductive status, but was additionally associated with actin in the apical epithelium on Day 16 of pregnancy. Vinculin interacted with phosphorylated focal adhesion kinase in the endometrial epithelium, and the interaction was dependent on estradiol-17β, a conceptus-secreted pregnancy-recognition factor in pigs. Furthermore, silencing vinculin in the endometrial epithelial cells negatively affected trophoblast adhesion to them. In conclusion, the influence of stage and reproductive status on the specific localization of actin and its binding proteins in the porcine endometrium suggests that they play a role in regulating the endometrial cytoskeleton. Moreover, vinculin may facilitate conceptus attachment to the epithelium by interacting with focal adhesion kinase.

Assembly, Biochemical Characterization, Immunogenicity, Adjuvanticity, and Efficacy of Shigella Artificial Invaplex

The native Invaplex (Invaplex_NAT) vaccine and adjuvant is an ion exchange-purified product derived from the water extract of virulent Shigella species. The key component of Invaplex_NAT is a high-molecular-mass complex (HMMC) consisting of the Shigella lipopolysaccharide (LPS) and the invasin proteins IpaB and IpaC. To improve product purity and immunogenicity, artificial Invaplex (Invaplex_AR) was developed using recombinant IpaB and IpaC proteins and purified Shigella LPS to assemble an HMMC consisting of all three components. Characterization of Invaplex_AR by various methods demonstrated similar characteristics as the previously reported HMMC in Invaplex_NAT. The well-defined Invaplex_AR vaccine consistently contained greater quantities of IpaB, IpaC, and LPS than Invaplex_NAT. Invaplex_AR and Invaplex_NAT immunogenicities were compared in mouse and guinea pig dose escalation studies. In both models, immunization induced antibody responses specific for Invaplex_NAT and LPS while Invaplex_AR induced markedly higher anti-IpaB and -IpaC serum IgG and IgA endpoint titers. In the murine model, homologous protection was achieved with 10-fold less Invaplex_AR than Invaplex_NAT and mice receiving Invaplex_AR lost significantly less weight than mice receiving the same amount of Invaplex_NAT. Moreover, mice immunized with Invaplex_AR were protected from challenge with both homologous and heterologous Shigella serotypes. Guinea pigs receiving approximately 5-fold less Invaplex_AR compared to cohorts immunized with Invaplex_NAT were protected from ocular challenge. Furthermore, adjuvanticity previously attributed to Invaplex_NAT was retained with Invaplex_AR. The second-generation Shigella Invaplex vaccine, Invaplex_AR, offers significant advantages over Invaplex_NAT in reproducibility, flexible yet defined composition, immunogenicity, and protective efficacy. IMPORTANCEShigella species are bacteria that cause severe diarrheal disease worldwide, primarily in young children. Treatment of shigellosis includes oral fluids and antibiotics, but the high burden of disease, increasing prevalence of antibiotic resistance, and long-term health consequences clearly warrant the development of an effective vaccine. One Shigella vaccine under development is termed the invasin complex or Invaplex and is designed to drive an immune response to specific antigens of the bacteria in an effort to protect an individual from infection. The work presented here describes the production and evaluation of a new generation of Invaplex. The improved vaccine stimulates the production of antibodies in immunized mice and guinea pigs and protects these animals from Shigella infection. The next step in the product's development will be to test the safety and immune response induced in humans immunized with Invaplex.

ITGAV (alpha v integrins) bind SPP1 (osteopontin) to support trophoblast cell adhesion

Attachment of the conceptus trophoblast (Tr) to the uterine luminal epithelium (LE) is critical for successful implantation. This study determined whether alpha v (av) integrins (ITGAV) directly mediate porcine trophoblast cell adhesion to secreted phosphoprotein 1 (SPP1, also known as osteopontin (OPN)) and examined the temporal/spatial expression of ITGAV, beta 3 (b3, ITGB3) and beta 6 (b6, ITGB6) integrin subunits, and SPP1, at the uterine-placental interface of pigs. Knockdown of ITGAV in porcine Tr (pTr2) cells by siRNA reduced pTr2 attachment to SPP1. In situ hybridization confirmed the presence of ITGAV, ITGB3 and ITGB6 mRNAs in uterine LE and conceptus Tr between Days 9 and 60 of gestation, with no change in the magnitude of expression over the course of pregnancy. Exogenous E2 or P4 did not affect ITGAV, ITGB3 and ITGB6 mRNA expression in the uteri of ovariectomized gilts. Immunofluorescence identified ITGAV, ITGB3 and SPP1 proteins in large aggregates at the uterine LE-placental Tr/chorion interface on Day 25, but aggregates were no longer observed by Day 50 of gestation. These results are the first to directly demonstrate that pTr2 cells engage ITGAV-containing integrin receptors to adhere to SPP1 and suggest that mechanical forces generated by tethering elongating conceptuses to uterine LE leads to assembly of focal adhesions containing ITGAV and SPP1; however, as placentation progresses, subsequent folding/interdigitation at the uterine-placental interface disperses mechanical forces resulting in the loss of focal adhesions.

Development of pre-implantation porcine blastocysts cultured within alginate hydrogel systems either supplemented with secreted phosphoprotein 1 or conjugated with Arg-Gly-Asp Peptide

Although deficiencies in porcine blastocyst elongation play a significant role in early embryonic mortality and establishment of within-litter developmental variation, the exact mechanisms of elongation are poorly understood. Secreted phosphoprotein 1 (SPP1) is increased within the uterine milieu during early porcine pregnancy and contains an Arg-Gly-Asp (RGD) peptide sequence that binds to cell surface integrins on the uterine endometrium and trophectoderm, promoting cell adhesion and migration. The aim of the present study was to evaluate the development of preimplantation porcine blastocysts encapsulated and cultured within alginate hydrogels either supplemented with SPP1 or conjugated with RGD. Blastocysts encapsulated within alginate hydrogels supplemented with SPP1 or conjugated with RGD had increased survival compared with non-encapsulated control blastocysts. In addition, the percentage of blastocysts encapsulated within RGD hydrogels that underwent morphological changes was greater than that of blastocysts encapsulated within standard alginate hydrogels or SPP1-supplemented hydrogels. Finally, only blastocysts encapsulated within RGD hydrogels had both increased expression of steroidogenic and immune responsiveness transcripts and increased 17β-oestradiol production, consistent with blastocysts undergoing elongation in vivo. These results illustrate the importance of the integrin-binding RGD peptide sequence for stimulating the initiation of blastocyst elongation.

Testosterone Deficiency Induces Changes of the Transcriptomes of Visceral Adipose Tissue in Miniature Pigs Fed a High-Fat and High-Cholesterol Diet

Testosterone deficiency causes fat deposition, particularly in visceral fat, and its replacement might reverse fat accumulation, however, the underlying mechanisms of such processes under diet-induced adiposity are largely unknown. To gain insights into the genome-wide role of androgen on visceral adipose tissue (VAT), RNA-Seq was used to investigate testosterone deficiency induced changes of VAT in miniature pigs fed a high-fat and high-cholesterol (HFC) diet among intact male pigs (IM), castrated male pigs (CM), and castrated male pigs with testosterone replacement (CMT) treatments. The results showed that testosterone deficiency significantly increased VAT deposition and serum leptin concentrations. Moreover, a total of 1732 differentially expressed genes (DEGs) were identified between any two groups. Compared with gene expression profiles in IM and CMT pigs, upregulated genes in CM pigs, i.e., LOC100520753 (CD68), LCN2, EMR1, S100A9, NCF1 (p47phox), and LEP, were mainly involved in inflammatory response, oxidation-reduction process, and lipid metabolic process, while downregulated genes in CM pigs, i.e., ABHD5, SPP1, and GAS6, were focused on cell differentiation and cell adhesion. Taken together, our study demonstrates that testosterone deficiency alters the expression of numerous genes involved in key biological processes of VAT accumulation under HFC diet and provides a novel genome-wide view on the role of androgen on VAT deposition under HFC diet, thus improving our understanding of the molecular mechanisms involved in VAT changes induced by testosterone deficiency.

Cellular Localization and Regulation of Expression of the PLET1 Gene in Porcine Placenta

The placenta expressed transcript 1 (PLET1) gene, which is expressed in placentas of pigs and mice, has been found to have a potential role in trophoblast cell fate decision in mice. Results of this study showed that the porcine PLET1 mRNA and protein were expressed exclusively in trophoblast cells on Days 15, 26, 50, and 95 of gestation (gestation length in the pig is 114 days), indicating that the PLET1 could be a useful marker for porcine trophoblast cells. Additionally, PLET1 protein was found to be redistributed from cytoplasm to the apical side of trophoblast cells as gestation progresses, which suggests a role of PLET1 in the establishment of a stable trophoblast and endometrial epithelial layers. In addition, two transcripts that differ in the 3′ UTR length but encode identical protein were identified to be generated by the alternative cleavage and polyadenylation (APA), and the expression of PLET1-L transcript was significantly upregulated in porcine placentas as gestation progresses. Furthermore, we demonstrated the interaction between the miR-365-3p and PLET1 gene using luciferase assay system. Our findings imply an important role of PLET1 in the placental development in pigs.

Secreted Phosphoprotein 1 and Sex-Specific Differences in Silica-Induced Pulmonary Fibrosis in Mice

BACKGROUND

Fibrotic lung diseases occur predominantly in males, and reports describe better survival in affected females. Male mice are more sensitive to silica-induced lung fibrosis than silica-treated female mice. Secreted phosphoprotein 1 (SPP1, also known as osteopontin) increases in pulmonary fibrosis, and Spp1 transcription may be regulated by estrogen or estrogen receptor-related receptors.

OBJECTIVE

We determined whether differences in silica-induced SPP1 levels contribute to sex differences in lung fibrosis.

METHODS

Male and female mice were treated with 0.2 g/kg intratracheal silica, and lung injury was assessed 1, 3, or 14 days post-exposure. Gene-targeted (Spp1-/-) mice, control Spp1+/+ (C57BL/6J) mice, ovariectomized (OVX) female mice, and estrogen-treated male mice were treated with silica, and lung injury was assessed.

RESULTS

Silica-induced SPP1 in lung tissue, bronchoalveolar lavage, and serum increased more in male than in female mice. Following silica treatment, bronchoalveolar lavage cell infiltrates decreased in female Spp1-/- mice compared with female Spp1+/+ mice, and lung hydroxyproline decreased in male Spp1-/- mice compared with male Spp1+/+ mice. OVX female mice had increased lung SPP1 expression in response to silica compared with silica-treated sham female mice. Silica-induced lung collagen and hydroxyproline (markers of fibrosis), and SPP1 levels decreased in estrogen-treated males compared with untreated males.

CONCLUSION

These findings suggest that sex-specific differences in SPP1 levels contribute to the differential sensitivity of male and female mice to the development of silica-induced fibrosis.

CITATION

Latoche JD, Ufelle AC, Fazzi F, Ganguly K, Leikauf GD, Fattman CL. 2016. Secreted phosphoprotein 1 and sex-specific differences in silica-induced pulmonary fibrosis in mice. Environ Health Perspect 124:1199-1207; http://dx.doi.org/10.1289/ehp.1510335.

Naringenin-induced migration of embrynoic trophectoderm cells is mediated via PI3K/AKT and ERK1/2 MAPK signaling cascades

For successful pregnancy, a well-coordinated network of growth factors, nutrients and hormones is required for fetal-maternal interactions. Naringenin, as a weak phytoestrogen, improves diabetes, inflammation, neuronal diseases, cardiovascular diseases and cancers. However, the role of naringenin in migration mechanism(s) of peri-implantation conceptuses is unknown. Therefore, in the present study, we determined the effects of naringenin on migration of porcine trophectoderm (pTr) cells, which is a known in vitro model for research on trophectoderm cell biology and placental-fetal developmental biology, in order to assess intracellular signal transduction pathways activated by naringenin. Migration of pTr cells increased in a dose-dependent manner in response to naringenin. Also, naringenin activated the phosphorylation of AKT and ERK1/2 proteins in a dose-dependent manner and those proteins were abundant mainly in the cytoplasm of naringenin-treated pTr cells. Within 30 min after treatment with 20 μM naringenin, the abundance of phosphorylated EKR1/2, P70S6K, P90RSK and S6K proteins increased, and then returned to basal levels by 120 min whereas the abundance of AKT increased gradually to 120 min post-treatment. However, the phosphorylation of AKT, P70S6K, P90RSK and S6K was reduced in naringenin-induced pTr cells pre-treated with a PI3K inhibitor (LY294002). Also, a MEK1/2 inhibitor (U0126) significantly decreased naringenin-induced phosphorylation of ERK1/2, P70S6K and S6K proteins in pTr cells. Moreover, the naringenin-stimulated migration of pTr cells was suppressed by LY294002 and U0126. Collectively, results of the present study suggest that naringenin supports migration of pTr cells through PI3K/AKT and ERK1/2 MAPK signaling pathways crucial for orchestrating conceptus-uterine interactions.

Lacrimal Gland Inflammation Deregulates Extracellular Matrix Remodeling and Alters Molecular Signature of Epithelial Stem/Progenitor Cells

PURPOSE

The adult lacrimal gland (LG) is highly regenerative and is able to repair itself even after substantial damage; however, this ability to regenerate is lost with the development of dry eye conditions in chronically inflamed LGs.This study compares changes in the cell adhesion and cell matrix molecules and stem cell transcription factors in the LGs of healthy mice and of two mouse models of Sjögren's syndrome: nonobese diabetic (NOD) and MRL-lpr/lpr (MRL/lpr) mice during the early stage of inflammation.

METHODS

The LGs from 12- to 13-week-old female MRL/lpr and male NOD mice along with their respective control strains were harvested and divided into three pieces and processed for quantitative (q) RT-PCR and qRT-PCR Arrays, histology, immunohistochemistry, and Western blotting.

RESULTS

The extracellular matrix (ECM) and adhesion molecules RT2-PCR array combined with protein expression data revealed changes in the expression of integrins, matrix metalloproteinases, and other molecules, which are associated largely with invasion, attachment, and expansion of the lymphocytic cells, whereas changes in the stem cell transcription factors revealed substantial decrease in expression of transcription factors associated with epithelial stem/progenitor cell lineage.

CONCLUSIONS

We concluded that the expression of several important ECM components is significantly deregulated in the LG of two murine models of Sjögren's syndrome, suggesting an alteration of the epithelial stem/progenitor cell niche. This may result in profound effects on localization, activation, proliferation, and differentiation of the LG stem/progenitor cells and, therefore, LG regeneration.

Analysis of Stage-Specific Gene Expression Profiles in the Uterine Endometrium during Pregnancy in Pigs

The uterine endometrium plays a critical role in regulating the estrous cycle and the establishment and maintenance of pregnancy in mammalian species. Many studies have investigated the expression and function of genes in the uterine endometrium, but the global expression pattern of genes and relationships among genes differentially expressed in the uterine endometrium during gestation in pigs remain unclear. Thus, this study investigated global gene expression profiles using microarray in pigs. Diverse transcriptome analyses including clustering, network, and differentially expressed gene (DEG) analyses were performed to detect endometrial gene expression changes during the different gestation stages. In total, 6,991 genes were found to be differentially expressed by comparing genes expressed on day (D) 12 of pregnancy with those on D15, D30, D60, D90 and D114 of pregnancy, and clustering analysis of detected DEGs distinguished 8 clusters. Furthermore, several pregnancy-related hub genes such as ALPPL2, RANBP17, NF1B, SPP1, and CST6 were discovered through network analysis. Finally, detected hub genes were technically validated by quantitative RT-PCR. These results suggest the complex network characteristics involved in uterine endometrial gene expression during pregnancy and indicate that diverse patterns of stage-specific gene expression and network connections may play a critical role in endometrial remodeling and in placental and fetal development to establish and maintenance of pregnancy in pigs.

Association of non-synonymous SNPs of <i>OPN</i> gene with litter size traits in pigs

Abstract. Osteopontin (OPN) gene is a secreted phosphoprotein which appears to play a key function in the conceptus implantation, placentation and maintenance of pregnancy in pigs. The objectives of this study were to verify the non-synonymous single nucleotide polymorphisms (SNPs) and their association with litter size traits in commercial Thai Large White pigs. A total of 320 Thai Large White sows were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Three SNPs at c.425G> A, c.573T> C and c.881C> T revealed amino acid exchange rates of p.110Ala> Thr, p.159Val> Ala and p.262Pro> Ser, respectively, and were then segregated. These three SNPs were significantly associated with total number born (TNB) and number born alive (NBA) traits. No polymorphisms of the two SNP markers (c.278A> G and c.452T> G) were observed in this study. Moreover, the SNPs at c.425G> A and c.573T> C were found to be in strong linkage disequilibrium. The association of OPN with litter size emphasizes the importance of porcine OPN as a candidate gene for reproductive traits in pig breeding.

Placentation, maternal-fetal interface, and conceptus loss in swine

Pregnancy is a delicate yet complex physiological process that requires fine-tuning of many factors (hormones, growth factors, cytokines, and receptors) between the mother and the conceptus to ensure the survival of the conceptus(es) to term. Any disturbance in the maternal-conceptus dialog can have detrimental effects on the affected conceptus or even the outcome of pregnancy as a whole. Being a litter-bearing species, such disruptions can lead to a loss of up to 45% of the totally healthy offspring during early (periattachment) and midgestation to late gestation in pigs. Although the exact mechanism is not entirely understood, several factors have been associated with the fetal loss including but not limited to uterine capacity, placental efficiency, genetics, nutrition, and deficits in vascularization at the maternal-fetal interface. Over the years, we investigated how immune cells are recruited to the porcine maternal-fetal interface and whether they contribute to vascularization. We also delineated how cytokines, chemokines, and cytokine destabilizing factors fine-tune inflammation and whether the cytokine shift from early to midpregnancy exists at the porcine maternal-fetal interface. Finally, we evaluated the role of microRNAs in regulating immune cell recruitment and their angiogenic functions during pregnancy. Collectively our research points out that the immune-angiogenesis axis at the porcine maternal interface is significantly involved in promoting new blood vessel development, regulating inflammatory responses and ultimately contributing to pregnancy success. In this review, we summarized current knowledge on spontaneous fetal loss in swine, with special attention to the mechanisms in immune reactivity and interplay at the maternal-fetal interface.

Extracellular Matrix can Recover the Downregulation of Adhesion Molecules after Cell Detachment and Enhance Endothelial Cell Engraftment

The low cell engraftment after transplantation limits the successful application of stem cell therapy and the exact pathway leading to acute donor cell death following transplantation is still unknown. Here we investigated if processes involved in cell preparation could initiate downregulation of adhesion-related survival signals, and further affect cell engraftment after transplantation. Human embryonic stem cell-derived endothelial cells (hESC-ECs) were suspended in PBS or Matrigel and kept at 4 °C. Quantitative RT-PCR analysis was used to test the adhesion and apoptosis genes’ expression of hESC-ECs. We demonstrated that cell detachment can cause downregulation of cell adhesion and extracellular matrix (ECM) molecules, but no obvious cell anoikis, a form of apoptosis after cell detachment, was observed. The downregulation of adhesion and ECM molecules could be regained in the presence of Matrigel. Finally, we transplanted hESC-ECs into a mouse myocardial ischemia model. When transplanted with Matrigel, the long-term engraftment of hESC-ECs was increased through promoting angiogenesis and inhibiting apoptosis, and this was confirmed by bioluminescence imaging. In conclusion, ECM could rescue the functional genes expression after cell detached from culture dish, and this finding highlights the importance of increasing stem cell engraftment by mimicking stem cell niches through ECM application.

Integrin beta 8 (ITGB8) regulates embryo implantation potentially via controlling the activity of TGF-B1 in mice

Integrins (ITGs) are mediators of cell-cell and cell-matrix interactions, which are also associated with embryo implantation processes by controlling the interaction of blastocyst with endometrium. During early pregnancy, ITGbeta8 (ITGB8) has been shown to interact with latent transforming growth factor (TGF) beta 1 (TGFB1) at the fetomaternal interface. However, the precise role of ITGB8 in the uterus and its association with embryo implantation has not been elucidated. Therefore, we attempted to ascertain the role of ITGB8 during the window of embryo implantation process by inhibiting its function or protein expression. Uterine plasma membrane-anchored ITGB8 was augmented at peri-implantation and postimplantation stages. A similar pattern of mRNA expression was also found during the embryo implantation period. An immunolocalization study revealed the presence of ITGB8 on luminal epithelial cells along with mild expression on the stromal cells throughout the implantation period studied; however, an intense fluorescence was noted only during the peri- and postimplantation stages. Bioneutralization and mRNA silencing of the uterine Itgb8 at preimplantation stage reduced the rate/frequency of embryo implantation and subsequent pregnancy, suggesting its indispensable role during the embryo implantation period. ITGB8 can also regulate the liberation of active TGFB1 from its latent complex, which, in turn, acts on SMAD2/3 phosphorylation (activation) in the uterus during embryo implantation. This indicates involvement of ITGB8 in the embryo implantation process through regulation of activation of TGFB1.

Activation of the transcription factor nuclear factor-kappa B in uterine luminal epithelial cells by interleukin 1 Beta 2: a novel interleukin 1 expressed by the elongating pig conceptus

Conceptus mortality is greatest in mammals during the peri-implantation period, a time when conceptuses appose and attach to the uterine surface epithelium while releasing proinflammatory molecules. Interleukin 1 beta (IL1B), a master proinflammatory cytokine, is released by the primate, rodent, and pig blastocyst during the peri-implantation period and is believed to be essential for establishment of pregnancy. The gene encoding IL1B has duplicated in the pig, resulting in a novel gene. Preliminary observations indicate that the novel IL1B is specifically expressed by pig conceptuses during the peri-implantation period. To verify this, IL1B was cloned from mRNA isolated from Day 12 pig conceptuses and compared with IL1B cloned from mRNA isolated from pig peripheral blood leukocytes (PBLs). The pig conceptuses, but not the PBLs, expressed a novel IL1B, referred to here as interleukin 1 beta 2 (IL1B2). Porcine endometrium was treated with recombinant porcine interleukin 1 beta 1 (IL1B1), the prototypical cytokine, and IL1B2 proteins. Immunohistochemistry and real-time RT-PCR were used to measure activation of nuclear factor-kappa B (NFKB) and NFKB-regulated transcripts, respectively, within the endometrium. Both IL1B1 and IL1B2 activated NFKB in the uterine luminal epithelium within 4 h. The NFKB activation and related gene expression, however, were lower in endometrium treated with IL1B2, suggesting that the conceptus-derived cytokine may have reduced activity within the uterus. In conclusion, the peri-implantation pig conceptus expresses a novel IL1B that can activate NFKB within the uterine surface epithelium, likely creating a proinflammatory microenvironment during establishment of pregnancy in the pig.

Osteopontin: a leading candidate adhesion molecule for implantation in pigs and sheep

Osteopontin (OPN; also known as Secreted Phosphoprotein 1, SPP1) is a secreted extra-cellular matrix (ECM) protein that binds to a variety of cell surface integrins to stimulate cell-cell and cell-ECM adhesion and communication. It is generally accepted that OPN interacts with apically expressed integrin receptors on the uterine luminal epithelium (LE) and conceptus trophectoderm to attach the conceptus to the uterus for implantation. Research conducted with pigs and sheep has significantly advanced understanding of the role(s) of OPN during implantation through exploitation of the prolonged peri-implantation period of pregnancy when elongating conceptuses are free within the uterine lumen requiring extensive paracrine signaling between conceptus and endometrium. This is followed by a protracted and incremental attachment cascade of trophectoderm to uterine LE during implantation, and development of a true epitheliochorial or synepitheliochorial placenta exhibited by pigs and sheep, respectively. In pigs, implanting conceptuses secrete estrogens which induce the synthesis and secretion of OPN in adjacent uterine LE. OPN then binds to αvβ6 integrin receptors on trophectoderm, and the αvβ3 integrin receptors on uterine LE to bridge conceptus attachment to uterine LE for implantation. In sheep, implanting conceptuses secrete interferon tau that prolongs the lifespan of CL. Progesterone released by CL then induces OPN synthesis and secretion from the endometrial GE into the uterine lumen where OPN binds integrins expressed on trophectoderm (αvβ3) and uterine LE (identity of specific integrins unknown) to adhere the conceptus to the uterus for implantation. OPN binding to the αvβ3 integrin receptor on ovine trophectoderm cells induces in vitro focal adhesion assembly, a prerequisite for adhesion and migration of trophectoderm, through activation of: 1) P70S6K via crosstalk between FRAP1/MTOR and MAPK pathways; 2) MTOR, PI3K, MAPK3/MAPK1 (Erk1/2) and MAPK14 (p38) signaling to stimulate trohectoderm cell migration; and 3) focal adhesion assembly and myosin II motor activity to induce migration of trophectoderm cells. Further large in vivo focal adhesions assemble at the uterine-placental interface of both pigs and sheep and identify the involvement of sizable mechanical forces at this interface during discrete periods of trophoblast migration, attachment and placentation in both species.

Cytokines from the pig conceptus: roles in conceptus development in pigs

Establishment of pregnancy in pigs involves maintaining progesterone secretion from the corpora lutea in addition to regulating a sensitive interplay between the maternal immune system and attachment of the rapidly expanding trophoblast for nutrient absorption. The peri-implantation period of rapid trophoblastic elongation followed by attachment to the maternal uterine endometrium is critical for establishing a sufficient placental-uterine interface for subsequent nutrient transport for fetal survival to term, but is also marked by the required conceptus release of factors involved with stimulating uterine secretion of histotroph and modulation of the maternal immune system. Many endometrial genes activated by the conceptus secretory factors stimulate a tightly controlled proinflammatory response within the uterus. A number of the cytokines released by the elongating conceptuses stimulate inducible transcription factors such as nuclear factor kappa B (NFKB) potentially regulating the maternal uterine proinflammatory and immune response. This review will establish the current knowledge for the role of conceptus cytokine production and release in early development and establishment of pregnancy in the pig.

mTOR signalling, embryogenesis and the control of lung development

The existence of a nutrient sensitive "autocatakinetic" regulator of embryonic tissue growth has been hypothesised since the early 20th century, beginning with pioneering work on the determinants of foetal size by the Australian physiologist, Thorburn Brailsford-Robertson. We now know that the mammalian target of rapamycin complexes (mTORC1 and 2) perform this essential function in all eukaryotic tissues by balancing nutrient and energy supply during the first stages of embryonic cleavage, the formation of embryonic stem cell layers and niches, the highly specified programmes of tissue growth during organogenesis and, at birth, paving the way for the first few breaths of life. This review provides a synopsis of the role of the mTOR complexes in each of these events, culminating in an analysis of lung branching morphogenesis as a way of demonstrating the central role mTOR in defining organ structural complexity. We conclude that the mTOR complexes satisfy the key requirements of a nutrient sensitive growth controller and can therefore be considered as Brailsford-Robertson's autocatakinetic centre that drives tissue growth programmes during foetal development.

Uterine responses to the preattachment embryo in domestic ungulates: recognition of pregnancy and preparation for implantation

The endometrium is a tissue newly evolved with the development of mammalian species. Its main function is the support of embryonic growth and development and the nutrition of the fetus. The species-specific differences in establishment and maintenance of pregnancy make the study of this tissue in various mammalian organisms particularly interesting. With the application of omics technologies to various mammalian species, many systematic studies of endometrial gene expression changes during the phase of establishment of pregnancy have been performed to obtain a global view of regulatory events associated with this biological process. This review summarizes the results of trancriptome studies of bovine, porcine, and equine endometrium. Furthermore, the results are compared between these species and to humans. Because an increasing number of studies suggest an important role of small regulatory RNAs (i.e., microRNAs), recent findings related to the regulation of endometrial functions and the development of the conceptus are presented.

Expression patterns of microRNAs in porcine endometrium and their potential roles in embryo implantation and placentation

Implantation and placentation are critical steps for successful pregnancy. The pig has a non-invasive placenta and the uterine luminal epithelium is intact throughout pregnancy. To better understand the regulation mechanisms in functions of endometrium at three certain gestational stages that are critical for embryo/fetal loss in pigs, we characterized microRNA (miRNA) expression profiles in the endometrium on days 15 (implantation period), 26 (placentation period) and 50 (mid-gestation period) of gestation. The differentially expressed miRNAs across gestational days were detected and of which, 65 miRNAs were grouped into 4 distinct categories according to the similarities in their temporal expression patterns: (1) categories A and B contain majority of miRNAs (51 miRNAs, such as the miR-181 family) that were down- or up-regulated between gestational days 15 and 26, respectively; (2) categories C and D (14 miRNAs) consist miRNAs that were down- or up-regulated between gestational days 26 and 50, respectively. The expression patterns represented by eleven miRNAs were validated by qPCR. The majority of miRNAs were in categories A and B, suggesting that these miRNAs were involved in regulation of embryo implantation and placentation. The pathway analysis revealed that the predicted targets were involved in several pathways, such as focal adhesion, cell proliferation and tissue remolding. Furthermore, we identified that genes well-known to affect embryo implantation in pigs, namely SPP1, ITGB3 and ESR1, contain the miR-181a or miR-181c binding sites using the luciferase reporter system. The present study revealed distinctive miRNA expression patterns in the porcine endometrium during the implantation, placentation or mid-gestation periods. Additionally, our results suggested that miR-181a and miR-181c likely play important roles in the regulation of genes and pathways that are known to be involved in embryo implantation and placentation in pigs.

The transcriptomic and proteomic effects of ectopic overexpression of miR-30d in human endometrial epithelial cells

miR-30d is known to be up-regulated during the acquisition of receptivity in the endometrium. In order to determine the transcriptomic and proteomic changes which occur after transient overexpression of miR-30d in primary endometrial epithelial cells, in vitro cultured human endometrial epithelial cells (hEECs) were studied experimentally. Two different miRNAs (scramble versus mimic; n = 15) were transiently transfected into primary hEECs from four different patients and were evaluated for mRNA and protein expression using Agilent's gene expression microarray and iTRAQ analysis techniques, respectively. A set of differentially expressed mRNAs were validated by qPCR and several differentially expressed proteins were validated by western blot. Finally, methylation differential immunoprecipitation (MeDIP) was used to validate the epigenetic changes in the H19 gene. The results showed that transient transfection with miR-30d miRNA induced the differential mRNA-expression of 176 genes (75 up-regulated and 101 down-regulated). Several of them have been associated with reproductive and endocrine system disorders, tissue development, and are implicated in epithelial cell proliferation. Also, the down-regulation of some genes such as H19 and N-methyltransferase (NNMT) may suggest that epigenetic alterations are induced. Furthermore, upstream effects of genes regulated by the estrogen receptor alpha 1 (ESR1) transcription factor have been predicted. Proteomic analysis identified 2290 proteins, of which 108 were differentially expressed (47 up-regulated and 61 down-regulated). Among these differentially expressed proteins DNA methyl transferase (DNMT)1 was found to be up-regulated; this protein participates in the maintenance of DNA methylation, supporting an epigenetic role for miR-30d. Finally MeDIP showed an increase in methylation in the H19 DMR region. In conclusion transient in vitro overexpression of the receptivity-up-regulated miRNA miR-30d in hEECs seems to activate genes which are associated with hormonal response and the epigenetic status of these cells.

The talin–integrin interface under mechanical stress

Interactions and force resistance of different β-integrin–talin complexes were analysed in a set of steered molecular dynamics simulations.

Expression and regulation of secreted phosphoprotein 1 in the bovine corpus luteum and effects on T lymphocyte chemotaxis

Secreted phosphoprotein 1 (SPP1) in the bovine corpus luteum (CL) regulates cell function during the transitional periods of luteinization and luteal regression. The objectives were to i) characterize SPP1 expression in the CL throughout the estrous cycle, ii) determine factors that regulate SPP1 expression in luteal cells, and iii) examine the role of SPP1 in lymphocyte chemotaxis, proliferation, and function. SPP1 mRNA was greater in fully functional (d10) CL and late cycle (d18) CL compared with developing (d4) CL. Additionally, SPP1 mRNA increased within 1 h and remained elevated 4 and 8 h following induction of luteolysis with prostaglandin (PG)F2α. Expression of the SPP1 receptor, β3 integrin, was not different throughout the estrous cycle but decreased following induction of luteolysis. Expression of CD44 increased during the estrous cycle but did not change during luteal regression. In cultured luteal cells, SPP1 mRNA was upregulated by PGF2α and/or tumor necrosis factor α. Western blots revealed the presence of both full-length SPP1 and multiple cleavage products in cultured luteal cells and luteal tissue. Depletion of endogenous SPP1 did not hinder luteal cell-induced lymphocyte proliferation or lymphocyte phenotype but did inhibit lymphocyte migration toward luteal cells. Based on these data, it is concluded that SPP1 is initially activated to establish and maintain cellular interactions between steroidogenic and nonsteroidogenic cells during the development of the CL. Upon induction of luteolysis, SPP1 serves as a signaling molecule to recruit or activate immune cells to facilitate luteal regression and tissue degradation.

Autocrine and paracrine mechanisms of prostaglandin E₂ action on trophoblast/conceptus cells through the prostaglandin E₂ receptor (PTGER2) during implantation

The conceptus and endometrium secrete large amounts of prostaglandin E₂ (PGE₂) into the porcine uterine lumen during the periimplantation period. We hypothesized that PGE₂ acts on conceptus/trophoblast cells through auto- and paracrine mechanisms. Real-time RT-PCR analysis revealed that PGE₂ receptor (PTGER)2 mRNA was 14-fold greater in conceptuses/trophoblasts on days 14-25 (implantation and early placentation period) vs preimplantation day 10-13 conceptuses (P < .05). Similarly, expression of PTGER2 protein increased during implantation. Conceptus expression of PTGER4 mRNA and protein did not differ on days 10-19. PGE₂ stimulated PTGER2 mRNA expression in day 15 trophoblast cells through PTGER2 receptor signaling. PGE₂ elevated aromatase expression and estradiol-17β secretion by trophoblast cells. Moreover, PGE₂ and the PTGER2 agonist, butaprost, increased the adhesive capacity of both human HTR-8/SVneo trophoblast and primary porcine trophoblast cells to extracellular matrix. This PGE₂-induced alteration in trophoblast cell adhesion to extracellular matrix was abolished by incubation of these cells with AH6809 (PTGER2 antagonist), ITGAVB3-directed tetrapeptide arg-gly-asp-ser or integrin ITGAVB3 antibody. PGE₂ stimulated adhesion of porcine trophoblast cells via the estrogen receptor and MEK/MAPK signaling pathway. PGE₂ induced phosphorylation of MAPK1/MAPK3 through PTGER2 and up-regulated expression of cell adhesion proteins such as focal adhesion kinase and intercellular adhesion molecule-1. Our study indicates that elevated PGE₂ in the periimplantation uterine lumen stimulates conceptus PTGER2 expression, which in turn promotes trophoblast adhesion via integrins, and synthesis and secretion of the porcine embryonic signal estradiol-17β. Moreover, the mechanism through which PGE₂ increases trophoblast adhesion is not species specific because it is PTGER2- and integrin-dependent in both porcine and human trophoblast cells.

Transcriptomic analysis of the porcine endometrium during early pregnancy and the estrous cycle

The goal of this study was to describe the alterations in the transcriptome of the endometrium in pigs during the beginning of implantation (days 15-16 of pregnancy) compared to cyclic pigs during the onset of luteolysis (days 15-16 of the estrous cycle). The global expression of genes in porcine gravid and non-gravid endometria was investigated using the Porcine (V2) Two-color gene expression microarray, 4 × 44 (Agilent, USA). Analysis of the microarray data showed that, of 589 accurately annotated genes, the expression of 266 genes was up-regulated and expression of 323 was down-regulated in the endometrium harvested during early pregnancy compared with the endometrium during the estrous cycle. In pregnant pigs, genes with the most significantly altered expression were involved in the following biological processes: the metabolic process, cellular process, cell communication, immune system process, developmental process, cell adhesion, antigen processing and presentation, antigen processing and presentation of peptide or polysaccharide antigen via major histocompatibility complex (MHC) class II, immune response, and the polysaccharide metabolic process. In the pregnant endometrium, cell adhesion molecules and steroid hormone biosynthesis pathways were the most significantly enriched biological pathways. Analysis of the interaction network among selected genes showed that androgen receptor (AR) encoding genes interact with genes involved in important processes occurring during early pregnancy. The bioinformatic analysis revealed information about the meaning of differentially expressed genes. The data provided new insight into the dynamic changes of the endometrial gene expression profile during days 15-16 of pregnancy.

Coculturing human endometrial epithelial cells and stromal fibroblasts alters cell-specific gene expression and cytokine production

OBJECTIVE

To determine the effects of coculturing endometrial epithelial cells (eEC) with paired endometrial stromal fibroblasts (eSF) on cell-specific gene expression and cytokine secretion patterns.

DESIGN

In vitro study.

SETTING

University research laboratory.

PATIENT(S)

Endometrial biopsies were obtained from premenopausal women.

INTERVENTION(S)

Polarized eEC and subject-paired eSF were cultured for 12.5 hours alone (monoculture) or combined in a two-chamber coculture system without cell-cell contact. Cells and conditioned media were analyzed for global gene expression and cytokine secretion, respectively. Purified, endometrial tissue-derived eEC and eSF isolated by fluorescent activated cell sorting (FACS) were used as noncultured controls.

MAIN OUTCOME MEASURE(S)

Cell-specific global gene expression profiling and analysis of secreted cytokines in eEC/eSF cocultures and respective monocultures.

RESULT(S)

Transepithelial resistance, diffusible tracer exclusion, expression of tight junction proteins, and apical/basolateral vectorial secretion confirmed eEC structural and functional polarization. Distinct transcriptomes of eEC and eSF were consistent with their respective lineages and their endometrial origin. Coculture of eEC with eSF resulted in altered cell-specific gene expression and cytokine secretion.

CONCLUSION(S)

This coculture model provides evidence that interactions between endometrial functionally polarized epithelium and stromal fibroblasts affect cell-specific gene expression and cytokine secretion underscoring their relevance when modeling endometrium in vitro.

Uterine receptivity and embryo-uterine interactions in embryo implantation: lessons from mice

Implantation is a process of the first feto-maternal encounter in the uterus. A competent blastocyst and a receptive uterus are critical for successful implantation. For an acquisition of uterine receptivity, the following conditions need to be satisfied in the uterine environments: the endometrial preparation with stromal proliferation and epithelial differentiation in the pre-receptive phase and proper interactions between the uterus and blastocyst later in the phase. Focusing on these points and primarily referring to the mouse in vivo evidence, this review article has shown detailed molecular mechanisms for successful implantation.

Arginine, leucine, and glutamine stimulate proliferation of porcine trophectoderm cells through the MTOR-RPS6K-RPS6-EIF4EBP1 signal transduction pathway

During the peri-implantation and early placentation periods in pigs, conceptuses (embryo and its extra-embryonic membranes) undergo dramatic morphological changes and differentiation that require the exchange of nutrients (histotroph) and gasses across the trophectoderm and a true epitheliochorial placenta. Of these nutrients, arginine (Arg), leucine (Leu), and glutamine (Gln) are essential components of histotroph; however, little is known about changes in their total amounts in the uterine lumen of cyclic and pregnant gilts and their effects on cell signaling cascades. Therefore, we determined quantities of Arg, Leu, and Gln in uterine luminal fluids and found that total recoverable amounts of these amino acids increased in pregnant but not cyclic gilts between Days 12 and 15 after onset of estrus. We hypothesized that Arg, Leu, and Gln have differential effects on hypertrophy, hyperplasia, and differentiated functions of trophectoderm cells that are critical to conceptus development. Primary porcine trophectoderm (pTr) cells treated with either Arg, Leu, or Gln had increased abundance of phosphorylated RPS6K, RPS6, and EIF4EBP1 compared to basal levels, and this effect was maintained for up to 120 min. When pTr cells were treated with Arg, Leu, and Gln, low levels of pRPS6K and pEIF4EBP1 were detected in the cytosol, but the abundance of nuclear pRPS6K increased. Immunofluorescence analyses revealed abundant amounts of pRPS6 protein in the cytoplasm of pTr cells treated with Arg, Leu, and Gln. These amino acids also increased proliferation of pTr cells. Furthermore, when Arg, Leu, and Gln were combined with siRNAs for either MTOR, RPTOR, or RICTOR, effects of those amino acids on proliferation of pTr cells were significantly inhibited. Collectively, these results indicate that Arg, Leu, and Gln act coordinately to stimulate proliferation of pTr cells through activation of the MTOR-RPS6K-RPS6-EIF4EBP1 signal transduction pathway.