Placental miR-1301 is dysregulated in early-onset preeclampsia and inversely correlated with maternal circulating leptin.

INTRODUCTION: miRNAs are small non-coding RNAs important for the regulation of mRNA in many organs including placenta. Adipokines and specifically leptin are known to be dysregulated in preeclampsia, but little is known regarding their regulation by miRNAs during pregnancy. METHODS: We performed high-throughput sequencing of small RNAs in placenta from 72 well-defined patients: 23 early-onset preeclampsia (PE), 26 late-onset PE and 23 controls. The regulation of some miRNAs was confirmed on qRT-PCR. Maternal circulating levels and placental mRNA of leptin, resistin and adiponectin were measured using Bio-Plex and qRT-PCR. RESULTS: We found that miR-1301, miR-223 and miR-224 expression was downregulated in early-onset PE, but not in late-onset PE, compared to controls. In silico analysis predicted the leptin gene (LEP) to be a target for all three miRNAs. Indeed, we found significant correlation between maternal circulating levels of leptin and placental LEP expression. In addition, we found a significant inverse correlation between maternal circulating leptin/placental LEP expression and placental miR-1301 expression levels. Interestingly, placental expression of miR-1301 was also correlated with newborn weight percentile and inversely correlated with both maternal systolic and diastolic blood pressure prior to delivery. DISCUSSION: Our results confirm that placenta is a major site of LEP expression during pregnancy. It further suggests that miR-1301 could be involved in the regulation of leptin during pregnancy and may play a role in early-onset PE. CONCLUSIONS: miR-1301 is dysregulated in early-onset preeclampsia and could possibly play a role in the regulation of leptin during pregnancy.

Expression profiling of autophagy associated genes in placentas of preeclampsia.

Autophagy, a mechanism of cell survival during times of stress, may be active in normal placental maintenance, cushioning the fetus from strain during fluctuations in nutrient availability. Moreover, in cases of placental insufficiency, often present in preeclampsia, autophagy may be defective. We used published microarray datasets to analyze differential expression of autophagy pathway genes. No statistically significant difference in autophagy associated gene expression was found in preeclamptic vs. normal placenta samples. Thus although preeclampsia displays many of the features suggestive of altered autophagy, impaired placental autophagy as a cause of preeclampsia is not supported by whole placental tissue differential expression profiling.

IFPA Meeting 2012 Workshop Report II: epigenetics and imprinting in the placenta, growth factors and villous trophoblast differentiation, role of the placenta in regulating fetal exposure to xenobiotics during pregnancy, infection and the placenta.

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2012 there were twelve themed workshops, four of which are summarized in this report. These workshops related to various aspects of placental biology: 1) epigenetics and imprinting in the placenta; 2) growth factors and villous trophoblast differentiation; 3) role of the placenta in regulating fetal exposure to xenobiotics during pregnancy; 4) infection and the placenta.

Review: Spatiotemporal dynamics of hCG/cAMP signaling and regulation of placental function.

The pregnancy hormone human chorionic gonadotropin (hCG) is essential to sustain early pregnancy and involved in regulation of progesterone production, decidualization, and cytotrophoblast differentiation. It binds to and activates the G-protein coupled luteinizing hormone/hCG-receptor, activating the cAMP/protein kinase A (PKA) pathway which results in the phosphorylation of specific intracellular target proteins. Specificity in cAMP signaling is ensured by generation of localized pools of cAMP controlled by phosphodiesterases and by discrete spatial and temporal activation of PKA in supramolecular signaling clusters inside the cell organized by A-kinase-anchoring proteins. Here we discuss spatiotemporal regulation of PKA signaling in response to hCG controlling placental function.

Docosahexaenoic acid stimulates tube formation in first trimester trophoblast cells, HTR8/SVneo.

Angiogenesis is a key factor in the placentation process and vascular remodeling that involves several growth factors such as vascular endothelial growth factor (VEGF) and angiopoietin-like protein 4 (ANGPTL4). PPARs are involved in the placentation process but not much information is available on whether their ligands such as fatty acids have any effects on these processes. We therefore investigated the effect of fatty acids (arachidonic acid, 20:4 n-6(ARA), eicosapentaenoic acid, 20:5 n-3(EPA), docosahexaenoic acid, 22:6 n-3 (DHA) and oleic acid, 18:1 n-9 (OA)) on tube formation (as a measure of angiogenesis) on matrigel in the first trimester trophoblast cells, HTR8/SVneo. In addition we also investigated the effects of fatty acids on expression of genes involved in angiogenesis (VEGF and ANGPTL4) and lipid metabolism in these cells. Gene expression was determined after incubating these cells with different fatty acids for 24 h using real-time qRT-PCR, whereas VEGF and ANGPTL4 proteins were measured by respective ELISA kits. Of all the fatty acids tested, DHA increased tube formation to the greatest extent. DHA-induced increase in tube length was 583%, 247% and 70% over control, OA and EPA, respectively (p < 0.05). In addition, DHA stimulated cell proliferation by 150% of these cells. Of all fatty acids investigated, only DHA stimulated VEGF mRNA expression and protein secretion compared with control. Unlike DHA, other fatty acids (OA, EPA, ARA) stimulated ANGPTL4 mRNA expression and protein secretion in these cells. An inhibitor of VEGF decreased DHA stimulated tube formation in these cells. Altogether these data indicate that DHA may potently influence the placentation process by stimulating tube formation and this effect may be mediated in part via VEGF in first trimester trophoblast cells.

Expression of liver X receptors in pregnancies complicated by preeclampsia.

Preeclampsia is a pregnancy-specific disorder associated with hyperlipidemia. Liver X receptor (LXR) alpha and LXRbeta are key regulators of lipid homeostasis. In the current study, we investigated expression of LXRalpha, LXRbeta and their target genes in human term placenta, decidua and subcutaneous adipose tissue from pregnancies complicated by preeclampsia. Furthermore, we analyzed the protein levels of LXRalpha and LXRbeta in placenta. We also analyzed lipid concentrations in term placental tissue. Gene expression of LXRalpha, LXRbeta and fatty acid transporter CD36 was significantly decreased in placental tissues, while increased expression was observed for LXRalpha in adipose tissue, from pregnancies complicated by preeclampsia. The placental protein level of LXRbeta was reduced, and there was a positive correlation between placental LXRbeta mRNA expression and placental free fatty acids in preeclampsia. Our results suggest a possible role for LXRbeta as a transcriptional regulator in preeclampsia.

Long-chain polyunsaturated fatty acids stimulate cellular fatty acid uptake in human placental choriocarcinoma (BeWo) cells.

Supplementation of long-chain polyunsaturated fatty acids (LCPUFAs) is advocated during pregnancy in some countries although very little information is available on their effects on placental ability to take up these fatty acids for fetal supply to which the fetal growth and development are critically dependent. To identify the roles of LCPUFAs on placental fatty acid transport function, we examined the effects of LCPUFAs on the uptake of fatty acids and expression of fatty acid transport/metabolic genes using placental trophoblast cells (BeWo). Following 24 h incubation of these cells with 100 microM of LCPUFAs (arachidonic acid, 20:4n-6, eicosapentaenoic acid, 20:5n-3, or docosahexaenoic acid, 22:6n-3), the cellular uptake of [(14)C] fatty acids was increased by 20-50%, and accumulated fatty acids were preferentially incorporated into phospholipid fractions. Oleic acid (OA, 18:1n-9), on the other hand, could not stimulate fatty acid uptake. LCPUFAs and OA increased the gene expression of ADRP whilst decreased the expression of ACSL3, ACSL4, ACSL6, LPIN1, and FABP3 in these cells. However, LCPUFAs but not OA increased expression of ACSL1 and ACSL5. Since acyl-CoA synthetases are involved in cellular uptake of fatty acids via activation for their channelling to lipid metabolism and/or for storage, the increased expression of ACSL1 and ACLS5 by LCPUFAs may be responsible for the increased fatty acid uptake. These findings demonstrate that LCPUFA may function as an important regulator of general fatty acid uptake in trophoblast cells and may thus have impact on fetal growth and development.

Liver X receptors mediate inhibition of hCG secretion in a human placental trophoblast cell line.

Liver X receptors (LXR) alpha and beta are important regulators of lipid homeostasis in liver, adipose and other tissues. However, no such information is available for the human placenta. We determined expression of both LXR alpha and beta in placental trophoblast cell lines, BeWo and JAR. Exposure of BeWo cells to a synthetic LXR agonist, T0901317, resulted in an increase in the amount of mRNA of LXR target genes, sterol regulatory element-binding protein-1 and fatty acid synthase. T0901317 also increased the synthesis of lipids. Moreover, T0901317 resulted in a reduced secretion of hCG during differentiation of these cells. Our data for the first time demonstrate a new role for LXRs in the human placenta.