Heewon Seo

Analysis of Lysophosphatidic Acid (LPA) Receptor and LPA-Induced Endometrial Prostaglandin-Endoperoxide Synthase 2 Expression in the Porcine Uterus

Lysophosphatidic acid (LPA), a simple phospholipid-derived mediator with diverse biological actions, acts through the specific G protein-coupled receptors endothelial differentiation gene (EDG) 2, EDG4, EDG7, and GPR23. Recent studies indicate a critical role for LPA receptor signaling in embryo implantation. To understand how LPA acts in the uterus during pregnancy in pigs, we evaluated: 1) spatial and temporal expression of LPA receptors in the uterine endometrium during the estrous cycle and pregnancy and in early-stage concepti, 2) LPA levels in uterine luminal fluids from d 12 of the estrous cycle and pregnancy, 3) effects of steroid hormones on EDG7 mRNA levels, and 4) effects of LPA on prostaglandin-endoperoxide synthase 2 (PTGS2) mRNA levels in the uterine endometrium using explant cultures. Of the four receptors, EDG7 was dominant, and its expression was regulated by pregnancy stage and status. EDG7 expression was highest on d 12 pregnancy, and localized to the luminal and glandular epithelium, and EDG7 mRNA levels were elevated by estrogen in the endometrium. EDG7 expression was also detected in concepti of d 12 and 15. LPA with various fatty acyl groups was present in the uterine lumen on d 12 of both the estrous cycle and pregnancy. LPA increased PTGS2 mRNA abundance in the uterine endometrium. These results indicate that LPA produced in the uterine endometrium may play a critical role in uterine endometrial function and conceptus development through EDG7-mediated PTGS2 expression during implantation and establishment of pregnancy in pigs.

Transcriptional activation of hypoxia-inducible factor-1α by HDAC4 and HDAC5 involves differential recruitment of p300 and FIH-1

P300 (uniprotkb:Q09472) physically interacts (MI:0218) with HIF1 alpha (uniprotkb:Q16665) by anti bait coimmunoprecipitation (MI:0006)

Regulatory Mechanism for Expression of IL1B Receptors in the Uterine Endometrium and Effects of IL1B on Prostaglandin Synthetic Enzymes During the Implantation Period in Pigs

ABSTRACT During the implantation period, the porcine conceptus secretes interleukin-1beta (IL1B) that may be involved in the establishment of pregnancy in pigs. However, the regulatory mechanism for IL1B receptor expression and the function of IL1B in the uterine endometrium are not well elucidated. In this study, we determined IL1B receptor expression in the uterine endometrium of pigs during pregnancy. IL1B receptor subtypes, IL1 receptor type I (IL1R1) and IL1 receptor accessory protein (IL1RAP) were expressed in the uterine endometrium with the expression being most abundant on Day 12 of pregnancy primarily in the luminal and glandular epithelial cells. Expression of IL1R1 mRNA increased in response to IL1B in a dose-dependent manner, and expression of IL1RAP mRNA increased in response to both IL1B and estradiol, indicating that expression of endometrial IL1B receptors was regulated cooperatively by IL1B and estrogen of conceptus origin. During the peri-implantation period, the porcine uterine endometrium actively synthesizes and secretes prostaglandins (PGs). IL1B increased expression of PTGS1 and PTGS2 genes that are rate-limiting for PG synthesis in the uterine endometrium. Collectively, the results indicated that IL1B regulates expression of IL1R1 and IL1RAP and stimulates expression of PTGS1 and PTGS2 that are considered to be the most rate-limiting enzymes for endometrial synthesis of PGs during the peri-implantation period of pregnancy in pigs.

Dynamic expression of calcium-regulatory molecules, TRPV6 and S100G, in the uterine endometrium during pregnancy in pigs.

Calcium ions have been implicated in the establishment and maintenance of pregnancy, but the regulatory mechanisms of calcium ions in the uterine endometrium and conceptus are not well understood in pigs. Recently, we showed that TRPV6, a calcium ion channel protein associated with cellular entry of calcium ions, is highly expressed in the uterine endometrium during the implantation period in pigs. In the present study, we investigated spatial and temporal expression and regulation of TRPV6 and S100G, an intracellular calcium-regulatory molecule, in the uterine endometrium during the estrous cycle and pregnancy in pigs. TRPV6 expression was maintained at significantly higher levels in the uterine endometrium during pregnancy compared with levels during the estrous cycle. TRPV6 transcripts and proteins were localized mainly to luminal epithelial cells (LE) and weakly to glandular epithelial cells (GE) and chorionic membrane (CM) during pregnancy. TRPV6 expression was also detected in conceptuses on Day (D) 12 and D15. TRPV6 mRNA levels in the endometrium were increased by estrogen treatment. S100G expression showed a biphasic pattern of increases on D12 of pregnancy and from D60 to term pregnancy, and it localized primarily to LE during early pregnancy and to LE, GE, and CM from D30 to term pregnancy. These results indicate that spatial and temporal expression of TRPV6 and S100G is dynamically regulated in the uterine endometrium during pregnancy and that endometrial regulation of calcium ion concentration by TRPV6 and S100G may be critical for the establishment and maintenance of pregnancy in pigs.

Salivary Lipocalin Is Uniquely Expressed in the Uterine Endometrial Glands at the Time of Conceptus Implantation and Induced by Interleukin 1Beta in Pigs

Uterine secretions are essential for the development of the conceptus during pregnancy. In pigs, various molecules, including transport proteins, growth factors, enzymes, and extracellular matrix proteins, are secreted into the uterine lumen. Our previous work identified salivary lipocalin (SAL1), a steroidal pheromone-binding protein, as present in the porcine uterus. To initiate studies on the role of SAL1 in the porcine uterus, we evaluated 1) the spatial and temporal expression of SAL1 in the uterine endometrium during the estrous cycle and pregnancy, and in the conceptus during early pregnancy; 2) secretion of SAL1 into the uterine lumen on Day (D) 12 of the estrous cycle and pregnancy; and 3) the effects of steroid hormones and cytokines on SAL1 mRNA levels. SAL1 was localized to glandular epithelial cells (GE) in the endometrium during the estrous cycle and pregnancy, with the highest level of SAL1 expression on D12 of pregnancy. In addition, SAL1 protein secretion into the uterine lumen was detected in uterine flushings on D12 of the estrous cycle and pregnancy, with higher levels on D12 of pregnancy. SAL1 protein, but not SAL1 transcript, was also detected in the conceptuses on D12 and D15. In explant culture experiments, SAL1 mRNA levels in the endometrium were increased by interleukin 1beta. The results of a GE- and implantation stage-specific expression and uterine secretion of SAL1 in the porcine uterus suggest that SAL1 present at the maternal-fetal interface may act as a histotroph and play an important role in the establishment of pregnancy.

Comprehensive Analysis of Prostaglandin Metabolic Enzyme Expression During Pregnancy and the Characterization of AKR1B1 as a Prostaglandin F Synthase at the Maternal-Conceptus Interface in Pigs

ABSTRACT Prostaglandins (PGs) are important lipid mediators regulating various reproductive processes in many species. In pigs, the expression pattern of PGE2 and PGF2α metabolic enzymes and the regulatory mechanism controlling PGE2 and PGF2α levels in the uterus during pregnancy are not completely understood. This study determined endometrial expression of the genes (PLA2G4A, PTGS1, PTGS2, PTGES, PTGES2, PTGES3, AKR1B1, CBR1, and HPGD) involved in PGE2 and PGF2α metabolism during the estrous cycle and pregnancy and measured levels of PGE2 and PGF2α in uterine endometrial tissues and uterine flushings at the time of conceptus implantation in pigs. Except PTGES3, expression of the genes studied changed in a pregnancy-stage-specific manner, and localization of PTGES, AKR1B1, CBR1, and HPGD mRNAs were cell-type specific in the uterine endometrium. Levels of both PGE2 and PGF2α in uterine endometrial tissues and uterine lumen were higher on Day 12 of pregnancy than those of the estrous cycle and affected by different morphology of spherical and filamentous conceptuses. Furthermore, we determined that endometrial expression of AKR1B1, known to encode a PGF2α synthase in other species, was increased by estrogen and interleukin-1beta and that AKR1B1 exhibited PGF2α synthase activity in the porcine uterine endometrium. These results in pigs indicate that the PGE2 and PGF2α metabolic enzymes are expressed stage specifically in the endometrium during pregnancy and regulate the abundance of PGE2 and PGF2α in the uterus at the time of implantation and that AKR1B1 may act as a major PGF synthase in the endometrium during early pregnancy.

Prostaglandin Transporters, ABCC4 and SLCO2A1, in the Uterine Endometrium and Conceptus During Pregnancy in Pigs

ABSTRACT Prostaglandins (PGs) are involved in many reproductive activities including luteolysis, maternal recognition of pregnancy, endometrial gene expression, conceptus development, and parturition in domestic animals. However, mechanisms by which PGE2 and PGF2alpha are modulated in the uterine endometrium and expression of ABCC4 and SLCO2A1, responsible for efficient transport of PGs across the cell membrane, in the endometrium during the estrous cycle and pregnancy are not fully understood in pigs. Therefore, we determined expression of ABCC4 and SLCO2A1, genes involved in transport of PGE2 and PGF2alpha in the uterine endometrium during the estrous cycle and pregnancy in pigs. ABCC4 and SLCO2A1 mRNAs were expressed in the uterine endometrium, most abundantly on Day 12 of pregnancy and during late pregnancy. Expression of ABCC4 mRNA and protein was localized mainly to uterine luminal epithelial (LE) and glandular epithelial (GE) cells, and expression of SLCO2A1 mRNA and protein was expressed primarily in uterine LE and blood vessels. Expression of ABCC4 and SLCO2A1 mRNAs was also detected in conceptuses during early pregnancy. In addition, explant culture experiments showed that increasing doses of interleukin 1B (IL1B) with estrogen and progesterone increased levels of ABCC4 and SLCO2A1 mRNAs in the uterine endometrium. These results indicate that expression of genes responsible for transport of PGE2 and PGF2alpha are dynamically regulated in the uterine endometrium during pregnancy and that ABCC4 and SLCO2A1 play critical roles in supporting the establishment and maintenance of pregnancy by regulating PG transport at the maternal–fetal interface in pigs.

Identification of differentially expressed genes in the uterine endometrium on day 12 of the estrous cycle and pregnancy in pigs.

Maternal recognition of pregnancy in pigs occurs approximately on Day (D) 12 of pregnancy and is critical for embryo implantation. The presence of the conceptus in the uterine lumen during this period changes uterine endometrial function to prepare for attachment of the conceptus to the endometrial epithelial cells and maintain luteal function in the ovary. Although much is known about endometrial gene expression, the genes expressed in the uterine endometria and the cellular and molecular mechanisms of those gene products during the period of implantation and maternal recognition of pregnancy in pigs are still not completely defined. To better understand the interactions between the maternal uterus and conceptus during the implantation process, we searched genes differentially expressed in the endometria on D12 of pregnancy compared to those on D12 of the estrous cycle. A new reverse transcription‐polymerase chain reaction (RT‐PCR)‐based method that involves annealing control primers (ACPs) was employed. Using 120 ACPs, we sequenced 12 differentially expressed genes (DEGs) and identified those genes using the Basic Local Alignment Search Tool (BLAST). Northern blot hybridization analysis confirmed the differential expression of those DEGs in the uterine endometrium. In situ hybridization analysis determined the cell‐type specific expression of the DEGs in the uterine endometrium. Further analysis of the DEGs found in this study will provide insights into the cellular and molecular basis of maternal and fetal interactions during the period of maternal recognition of pregnancy in the pig. Mol. Reprod. Dev. 76: 75–84, 2009.

Swine Leukocyte Antigen-DQ Expression and Its Regulation by Interferon-Gamma at the Maternal-Fetal Interface in Pigs

ABSTRACT Successful pregnancy requires an appropriate intrauterine immune response to the conceptus, which is a semiallograft within the uterus. We reported that swine leukocyte antigen-DQA (SLA-DQA), a major histocompatibility complex (MHC) class II gene, is expressed in the uterine endometrium at the time of conceptus implantation in pigs. Because MHC molecules play critical roles in the immune system, SLA-DQ was hypothesized to be involved in immune regulation during pregnancy. Therefore, we examined expression of SLA-DQ in uterine endometrial tissues obtained during the estrous cycle and pregnancy. SLA-DQA and SLA-DQB mRNAs were detected as 1.3-kb and 1.2-kb bands, respectively. Real-time RT-PCR analysis indicated that SLA-DQA and SLA-DQB mRNA expression was affected by day and pregnancy status, with the highest expression on Day 15 of pregnancy. SLA-DQ was localized primarily to subepithelial stromal cells and endothelial cells of the uterus. Using endometrial explant cultures from Day 12 of the estrous cycle, we determined that expression of SLA-DQA and SLA-DQB mRNAs increased in response to interferon-gamma (IFNG), which is produced by pig conceptus trophectoderm between Days 14 and 18 of pregnancy. The abundance of SLA-DQ protein was less in endometria from gilts with conceptuses resulting from somatic cell nuclear transfer compared with endometria from gilts with conceptuses resulting from natural mating. These results support our hypothesis that SLA-DQ is expressed in response to IFNG from the conceptus, and likely regulates immune response at the maternal-fetal interface to support the maintenance of pregnancy in pigs.

Analysis of the Lysophosphatidic Acid-Generating Enzyme ENPP2 in the Uterus During Pregnancy in Pigs

ABSTRACT Lysophosphatidic acid (LPA), a simple phospholipid, plays a critical role in the establishment of pregnancy in pigs. LPA production is mediated by the action of ENPP2, a secreted lysophospholipase D (lysoPLD) that converts lysophosphatidylcholine to LPA. However, the mechanism that regulates LPA production by ENPP2 in the porcine uterus is not well understood. In this study, we evaluated ENPP2 expression during the estrous cycle and pregnancy in the uterine endometrium and in early stage conceptuses. We also evaluated lysoPLD activity in the uterine lumen. ENPP2 transcripts and proteins were detected in the uterine endometrium at all stages of the estrous cycle and pregnancy, with higher levels on Day (D) 12 and D15 of the estrous cycle and pregnancy. ENPP2 expression was localized mainly in luminal and glandular epithelial cells in the endometrium and was also detected in conceptuses on D12 of pregnancy. Secreted ENPP2 protein was detected in fluid flushing samples from the uterine lumen on D12 of the estrous cycle and pregnancy, with higher levels on D12 of pregnancy. LysoPLD activity was detected in uterine flushings on D12 of the estrous cycle and pregnancy, with higher levels on D12 of pregnancy. This study showed that uterine endometrium and conceptuses produce ENPP2 and secreted it into the uterine lumen where it has lysoPLD activity. These results suggest that ENPP2 may play an important role in the establishment of pregnancy in pigs by regulating LPA production at the maternal–conceptus interface.