Placental origins of adverse pregnancy outcomes: potential molecular targets: an Executive Workshop Summary of the Eunice Kennedy Shriver National Institute of Child Health and Human Development

Although much progress is being made in understanding the molecular pathways in the placenta that are involved in the pathophysiology of pregnancy-related disorders, a significant gap exists in the utilization of this information for the development of new drug therapies to improve pregnancy outcome. On March 5-6, 2015, the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health sponsored a 2-day workshop titled Placental Origins of Adverse Pregnancy Outcomes: Potential Molecular Targets to begin to address this gap. Particular emphasis was given to the identification of important molecular pathways that could serve as drug targets and the advantages and disadvantages of targeting these particular pathways. This article is a summary of the proceedings of that workshop. A broad number of topics were covered that ranged from basic placental biology to clinical trials. This included research in the basic biology of placentation, such as trophoblast migration and spiral artery remodeling, and trophoblast sensing and response to infectious and noninfectious agents. Research findings in these areas will be critical for the formulation of the development of future treatments and the development of therapies for the prevention of a number of pregnancy disorders of placental origin that include preeclampsia, fetal growth restriction, and uterine inflammation. Research was also presented that summarized ongoing clinical efforts in the United States and in Europe that has tested novel interventions for preeclampsia and fetal growth restriction, including agents such as oral arginine supplementation, sildenafil, pravastatin, gene therapy with virally delivered vascular endothelial growth factor, and oxygen supplementation therapy. Strategies were also proposed to improve fetal growth by the enhancement of nutrient transport to the fetus by modulation of their placental transporters and the targeting of placental mitochondrial dysfunction and oxidative stress to improve placental health. The roles of microRNAs and placental-derived exosomes, as well as messenger RNAs, were also discussed in the context of their use for diagnostics and as drug targets. The workshop discussed the aspect of safety and pharmacokinetic profiles of potential existing and new therapeutics that will need to be determined, especially in the context of the unique pharmacokinetic properties of pregnancy and the hurdles and pitfalls of the translation of research findings into practice. The workshop also discussed novel methods of drug delivery and targeting during pregnancy with the use of macromolecular carriers, such as nanoparticles and biopolymers, to minimize placental drug transfer and hence fetal drug exposure. In closing, a major theme that developed from the workshop was that the scientific community must change their thinking of the pregnant woman and her fetus as a vulnerable patient population for which drug development should be avoided, but rather be thought of as a deprived population in need of more effective therapeutic interventions.

A Prolactin Family Paralog Regulates Placental Adaptations to a Physiological Stressor

The prolactin (PRL) family of hormones and cytokines participates in the regulation of optimal reproductive performance in the mouse and rat. Members of the PRL family are expressed in the anterior pituitary, uterus, and/or placenta. In the present study, we investigated the ontogeny of PRL family 7, subfamily b, member 1 (PRL7B1; also called PRL-like protein-N, PLP-N) expression in the developing mouse placenta and established a mouse model for investigating the biological function of PRL7B1. Transcripts for Prl7b1 were first detected on Gestation Day (d) 8.5. From gestation d8.5 through d14.5, Prl7b1 was expressed in trophoblast cells residing at the interface between maternal mesometrial decidua and the developing placenta. On gestation d17.5, the predominant cellular source of Prl7b1 mRNA was migratory trophoblast cells invading into the uterine mesometrial decidua. The Prl7b1 null mutant allele was generated via replacement of the endogenous Prl7b1 coding sequence with beta-galactosidase (LacZ) reporter and neomycin cassettes. The mutant Prl7b1 allele was successfully passed through the germline. Homozygous Prl7b1 mutant mice were viable and fertile. Under standard animal housing conditions, Prl7b1 had undetectable effects on placentation and pregnancy. Hypoxia exposure during pregnancy evoked adaptations in the organization of the wild-type placenta that were not observed in Prl7b1 null placentation sites. In summary, PRL7B1 is viewed as a part of a pathway regulating placental adaptations to physiological stressors.

CITED2 modulation of trophoblast cell differentiation: insights from global transcriptome analysis

Trophoblast stem (TS) cells possess the capacity to differentiate along a multi-lineage pathway yielding several specialized cell types. The regulatory network controlling trophoblast cell differentiation is poorly understood. Cbp/p300-interacting transactivator with Glu/Asp-rich carboxy-terminal domain, 2 (CITED2) has been implicated in the regulation of placentation; however, we know little about how CITED2 acts to influence trophoblast cells. Rat Rcho-1 TS cells can be manipulated to proliferate or differentiate into specialized trophoblast lineages and are an excellent model for investigating trophoblast differentiation. CITED2 transcript and protein showed a robust induction during Rcho-1 TS cell differentiation. We used an shRNA knockdown approach to disrupt CITED2 expression in order to investigate its involvement in trophoblast cell differentiation. RNA-sequencing was used to examine the impact of CITED2 on trophoblast cell differentiation. CITED2 disruption affected the differentiating trophoblast cell transcriptome. CITED2 possessed a prominent role in the regulation of cell differentiation with links to several signal transduction pathways and to hypoxia-regulated and coagulation processes. In summary, our findings indicate that CITED2 contributes to the regulation of trophoblast cell differentiation.

Identification of target genes for a prolactin family paralog in mouse decidua

Prolactin family 8, subfamily a, member 2 (PRL8A2; also called decidual prolactin-related protein; dPRP) is a member of the expanded prolactin family. PRL8A2 is expressed in the uterine decidua and contributes to pregnancy-dependent adaptations to hypoxia. The purpose of this study was to identify gene targets for PRL8A2 action within the uteroplacental compartment. Affymetrix DNA microarray analysis was performed for RNA samples from WT and Prl8a2 null tissues. Validation of the DNA microarray was performed using quantitative RT-PCR. Nine genes were confirmed with decreased expression in Prl8a2 null tissues (e.g., Klk7, Rimklb, Arhgef6, Calm4, Sprr2h, Prl4a1, Ccl27, Lipg, and Htra3). These include potential decidual, endothelial and trophoblast cell targets positively regulated by PRL8A2. A significant upregulation of Derl3, Herpud1, Creld2, Hsp90b1, Ddit3 and Hspa5 was identified in Prl8a2 null tissues, reflecting an increased endoplasmic reticulum (ER) stress response. ER stress genes were prominently expressed in the uterine decidua. We propose that PRL8A2 is a mediator of progesterone-dependent modulation of intrauterine responses to physiological stressors.

The impact of thiamine supplementation on blood pressure, serum lipids and C-reactive protein in individuals with hyperglycemia: a randomised, double-blind cross-over trial

BACKGROUND

The adverse effects of hyperglycemia may be potentiated when it is accompanied with hypertension and dyslipidemia. This study assessed the effects of high dose thiamine on blood pressure, serum lipids and C-reactive protein (hs-CRP) in individuals with impaired glucose metabolism.

METHODS

This was a double-blind, randomised trial, where 12 hyperglycemic subjects (10 cases of impaired glucose tolerance and 2 new cases of type 2 diabetes mellitus) received both placebo and thiamine capsules (3 × 100 mg/day) for six weeks in a cross-over manner. Anthropometric measurements, systolic and diastolic blood pressure (SBP & DBP), serum cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, hs-CRP and thiamine status were evaluated at the start, after three weeks and on the completion of each arm.

RESULTS

DBP was significantly decreased in participants consuming thiamine supplements for six weeks (67.9 ± 5.8 mm Hg) relative to baseline (71.4 ± 7.4 mm Hg, p=0.005) and week 3 (70.9. ± 5.8 mm Hg, p=0.02). This was accompanied with a tendency toward a lower SBP at week six relative to baseline (116.5 ± 11.0 vs. 120.7 ± 15.3 mm Hg, p=0.06). Also, mean arterial pressure (MAP) determined in the supplement arm after six weeks was significantly lower than baseline (84.1 ± 6.5 vs. 87.8 ± 9.0, p=0.005). These variables did not change in the placebo arm. No significant change was detected in the supplement or placebo arms when lipid profile and hs-CRP were assessed.

CONCLUSION/INTERPRETATION

High dose thiamine supplementation may have beneficial effects on the blood pressure of individuals with hyperglycemia at early stages, and may have a role in the prevention of further vascular complications.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12611000051943.

Neonatal Progesterone Programs Adult Uterine Responses to Progesterone and Susceptibility to Uterine Dysfunction

In this report, we investigated the consequences of neonatal progesterone exposure on adult rat uterine function. Female pups were subcutaneously injected with vehicle or progesterone from postnatal days 3 to 9. Early progesterone exposure affected endometrial gland biogenesis, puberty, decidualization, and fertility. Because decidualization and pregnancy success are directly linked to progesterone action on the uterus, we investigated the responsiveness of the adult uterus to progesterone. We first identified progesterone-dependent uterine gene expression using RNA sequencing and quantitative RT-PCR in Holtzman Sprague-Dawley rats and progesterone-resistant Brown Norway rats. The impact of neonatal progesterone treatment on adult uterine progesterone responsiveness was next investigated using quantitative RT-PCR. Progesterone resistance affected the spectrum and total number of progesterone-responsive genes and the magnitude of uterine responses for a subset of progesterone targets. Several progesterone-responsive genes in adult uterus exhibited significantly dampened responses in neonatally progesterone-treated females compared with those of vehicle-treated controls, whereas other progesterone-responsive transcripts did not differ between female rats exposed to vehicle or progesterone as neonates. The organizational actions of progesterone on the uterus were dependent on signaling through the progesterone receptor but not estrogen receptor 1. To summarize, neonatal progesterone exposure leads to disturbances in endometrial gland biogenesis, progesterone resistance, and uterine dysfunction. Neonatal progesterone effectively programs adult uterine responsiveness to progesterone.

Vitamin D status and insulin sensitivity are novel predictors of resting metabolic rate: a cross-sectional analysis in Australian adults

PURPOSE

Resting metabolic rate (RMR) accounts for two-thirds of the total energy expenditure in sedentary individuals. After accounting for traditional factors, there still remains a considerable unexplained variance in RMR. There is a pandemic of obesity and metabolic syndrome (MetS) which coexists with a high prevalence of vitamin D insufficiency. The aim of this study was to evaluate the potential effects of vitamin D status, insulin sensitivity (IS) and the metabolic syndrome (MetS) on RMR in Australian adults.

METHODS

RMR, respiratory quotient (RQ), McAuley's insulin sensitivity index, fat mass (FM), fat-free mass (FFM) and vitamin D status were assessed in Australian adults. The presence of MetS was evaluated by current standard criteria. Predictors of RMR were examined through multiple linear regression based on stepwise and backward regression approaches with attention to multi-collinearity. All analyses were conducted on SPSS version 21.

RESULTS

One hundred and twenty-seven participants (45 men, 82 women), aged 53.4 ± 11.7 years and BMI 31.9 ± 5.2 kg/m(2), were included. Forty-one subjects were insufficient in vitamin D status (<50 nmol/L), and 75 participants had the MetS. A parsimonious regression model explained 85.8 % of RMR and was given by: RMR (kJ/d) = 1931 + 83.5 × FFM (kg) + 29.5 × FM (kg) + 5.65 × 25(OH)D (nmol/L) - 17.6 × age (years) - 57.51 × IS.

CONCLUSION

Vitamin D status and IS are novel independent predictors of RMR in adults. Future studies could validate a causal role for these factors in human energy metabolism.

A systematic review protocol examining the effect of vitamin D supplementation on endothelial function

INTRODUCTION

Vitamin D has potential benefits for extraskeletal health. These could include an anti-inflammatory effect as well as a reduction in endothelial dysfunction. We aim to provide quality evidence for the hypothesis that supplementation with vitamin D will improve endothelial function (EF), possibly through the abrogation of systemic inflammation.

METHODS AND ANALYSIS

We will conduct a systematic review of all randomised controlled trials on vitamin D supplementation and EF lasting 12 weeks or more. The search will cover the period 2000-2015 and include studies that describe direct measures of EF, markers of endothelial cell (EC) activation and if concurrently reported, indicators of systemic inflammation. Study selection will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and study quality will be assessed by the Jadad score in addition to an evaluation of allocation concealment and data analysis. If sufficient data are available, a meta-analysis will be conducted. The effect sizes will be generated using Hedges' g score, for both fixed and random effect models. I(2) statistics and Galbraith plots will be used to assess heterogeneity and identify their potential sources. Potential publication and small sample size bias will be assessed by visual inspections of funnel plots and also Egger's test. Meta-regression analysis (if feasible) will be conducted with restricted maximum likelihood (REML) estimation method, controlling for potential confounders (demographics, study methods, location, etc). A backward elimination process will be applied in the regression modelling procedure. Subgroup analysis, conditional on number of studies retrieved and their sample size, will be stratified on participant disease category, total dose administered, degree of 25(OH)D change and type of supplement used.

ETHICS AND DISSEMINATION

Formal ethical approval is not required as primary data will not be collected. The results will be disseminated through a peer-reviewed publication, conference presentation and the popular press.

TRIAL REGISTRATION NUMBER

International Prospective Register for Systematic Reviews (PROSPERO) number CRD42014013523.

Adaptive mechanisms controlling uterine spiral artery remodeling during the establishment of pregnancy

Implantation of the embryo into the uterus triggers the initiation of hemochorial placentation. The hemochorial placenta facilitates the acquisition of maternal resources required for embryo/fetal growth. Uterine spiral arteries form the nutrient supply line for the placenta and fetus. This vascular conduit undergoes gestation stage-specific remodeling directed by maternal natural killer cells and embryo-derived invasive trophoblast lineages. The placentation site, including remodeling of the uterine spiral arteries, is shaped by environmental challenges. In this review, we discuss the cellular participants controlling pregnancy-dependent uterine spiral artery remodeling and mechanisms responsible for their development and function.

Genetic polymorphisms of phase I and phase II metabolic enzymes as modulators of lung cancer susceptibility

OBJECTIVES

Tobacco exposure remains the main etiologic factor for lung cancer (LC). Interactions between environment and individual genetic profile are particularly important for this disease. The aim of this study was to evaluate the contribution of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 polymorphisms for the susceptibility to LC in a Portuguese population considering their demographic and clinical characteristics.

MATERIALS AND METHODS

A total of 200 LC and 247 controls subjects from the Centre of Portugal were studied. Clinical and demographic characteristics were collected from clinical files and by individual questionnaires. Polymorphisms of CYP1A1*2A, CYP1A1*2C, CYP2D6*4, GSTP1, GSTM1, GSTT1 and NAT2 were genotyped using PCR-RFLP, PCR multiplex, ARMS and real time.

RESULTS

Gender, family history of cancer, smoke cessation and alcohol consumption were independent risk factors (p < 0.05). Associations found between phases I and II genes and LC population reveal a sex dependent distribution. Logistic regression analysis demonstrates that enhanced activation by CYPs, associated by reduced or loss of function of phase II enzymes, can lead to a greater risk. GSTP1 and NAT2 polymorphisms studied have a significant contribution for the histological tumour types and the presence of metastases, at time of diagnosis, respectively, when males with smoking habits were considered.

CONCLUSION

Multiple interactions between environment and individual characteristics are clearly associated to this disease. Variants of the detoxification genes may act synergistically contributing to this disease and modifying the risk posed by smoking and sex. The GSTT1*0 and GSTP1 (Ile462Val) might contribute to the malignant phenotype through different mechanisms.

Profile of depressive symptoms in women in the perinatal and outside the perinatal period: similar or not?

PURPOSES

To analyze which Beck Depression Inventory-II (BDI-II) and Postpartum Depression Screening Scores (PDSS) total and dimensional scores, as well as symptomatic answers proportions significantly differ between women in the perinatal period (pregnant/postpartum) without major depression, with major depression and women outside the perinatal period.

METHODS

572 pregnant women in the third trimester completed Beck Depression Inventory-II and Postpartum Depression Screening Scale and were assessed with the Diagnostic Interview for Genetic Studies. 417 of these were also assessed (with the same instruments) at three months postpartum. Ninety non-pregnant women or that did not have a child in the last year (mean age=29.42±7.159 years) also filled in the questionnaires.

RESULTS

Non-depressed pregnant women showed lower scores than depressed pregnant women and higher scores than women outside the perinatal period in the BDI-II total score and in its Somatic-Anxiety dimension. Non-depressed postpartum women showed significantly higher scores than women outside the perinatal period only at Sleep/Eating Disturbances. Compared to women outside the perinatal period, pregnant women without depression presented higher scores only in the somatic items. Women with vs. without depression in the postpartum period did not significantly differ and both presented higher scores than women outside the perinatal period in the proportions of loss of energy and sleep changes.

LIMITATIONS

Women outside the perinatal period were not diagnosed for the presence of a depressive disorder, but their BDI-II mean score was similar to the figures reported worldwide regarding women in childbearing age.

CONCLUSION

In the perinatal period, most particularly at pregnancy, women experience significant somatic changes even if not clinically depressed. Cognitive-affective symptoms are more useful when assessing the presence of perinatal depression.

Vitamin D supplementation and body weight status: a systematic review and meta-analysis of randomized controlled trials

Vitamin D is anticipated to have many extra-skeletal health benefits. We questioned whether supplementation with the vitamin influenced body weight and composition. A systematic review and meta-analysis was conducted on high-quality, randomized controlled trials (RCTs) that had supplemented vitamin D without imposing any caloric restriction. Eighteen trials reporting either body weight, body mass index (BMI), fat mass (FM), percentage fat mass (%FM) or lean body mass (LBM) met our criteria. Twelve studies provided the required data for the meta-analysis. Vitamin D supplementation did not influence the standardized mean difference (SMD) for body weight, FM, %FM or LBM. A small but non-significant decrease in BMI (SMD = -0.097, 95% confidence interval: [-0.210, 0.016], P = 0.092) was observed. Meta-regression confirmed that neither the absolute vitamin D status achieved nor its change from baseline influenced the SMD of any obesity measure. However, increasing age of the subjects predicted a shift in the SMD for FM towards the placebo treatment, whereas a greater percentage of women in these studies favoured a decrease in FM following vitamin D. Vitamin D supplementation did not decrease measures of adiposity in the absence of caloric restriction. A potential confounding by age and gender was encountered.

Generation of Esr1-knockout rats using zinc finger nuclease-mediated genome editing

Estrogens play pivotal roles in development and function of many organ systems, including the reproductive system. We have generated estrogen receptor 1 (Esr1)-knockout rats using zinc finger nuclease (ZFN) genome targeting. mRNAs encoding ZFNs targeted to exon 3 of Esr1 were microinjected into single-cell rat embryos and transferred to pseudopregnant recipients. Of 17 live births, 5 had biallelic and 1 had monoallelic Esr1 mutations. A founder with monoallelic mutations was backcrossed to a wild-type rat. Offspring possessed only wild-type Esr1 alleles or wild-type alleles and Esr1 alleles containing either 482 bp (Δ482) or 223 bp (Δ223) deletions, indicating mosaicism in the founder. These heterozygous mutants were bred for colony expansion, generation of homozygous mutants, and phenotypic characterization. The Δ482 Esr1 allele yielded altered transcript processing, including the absence of exon 3, aberrant splicing of exon 2 and 4, and a frameshift that generated premature stop codons located immediately after the codon for Thr157. ESR1 protein was not detected in homozygous Δ482 mutant uteri. ESR1 disruption affected sexually dimorphic postnatal growth patterns and serum levels of gonadotropins and sex steroid hormones. Both male and female Esr1-null rats were infertile. Esr1-null males had small testes with distended and dysplastic seminiferous tubules, whereas Esr1-null females possessed large polycystic ovaries, thread-like uteri, and poorly developed mammary glands. In addition, uteri of Esr1-null rats did not effectively respond to 17β-estradiol treatment, further demonstrating that the Δ482 Esr1 mutation created a null allele. This rat model provides a new experimental tool for investigating the pathophysiology of estrogen action.

The FOS transcription factor family differentially controls trophoblast migration and invasion

Extravillous trophoblast invasion is a fundamental component of human placentation. Invading trophoblast cells promote blood flow to the conceptus by actively remodeling the uterine vasculature. The extent of trophoblast invasion is tightly regulated; aberrant invasion is linked with several obstetrical complications. However, the transcriptional networks responsible for controlling the extent of trophoblast invasion are not well defined. Previous studies have identified high levels of FOS (FOS, FOSB, FOS-like (FOSL) 1, and FOSL2) proteins in extravillous trophoblast cells. These proteins form part of the activating protein-1 (AP-1) transcription factor complex and are implicated in regulating gene networks controlling cellular invasion in diverse biological systems. Therefore, we hypothesized that FOS family proteins play a role in regulating trophoblast invasion. We assessed expression of FOS family proteins in trophoblast cell lines and human placentae at different gestational ages. FOS, FOSB, and FOSL1 proteins were robustly increased in trophoblast cells subject to wound-based migration assays as well as Matrigel-based invasion assays. FOS knockdown resulted in cessation of proliferation and an induction of migration and invasion concomitant with robust expression of matrix metalloproteinase (MMP) 1, MMP3, and MMP10. Conversely, FOSL1 knockdown abrogated trophoblast migration and invasion and inhibited the production of MMP1, MMP3, and MMP10. In human placenta, FOS was expressed in proximal anchoring villi in conjunction with phospho-ERK. FOSL1 was temporally expressed only in the distal-most extravillous trophoblast cells, which represent a migratory cell population. Therefore, FOS and FOSL1 exert opposing effects on trophoblast invasion.

Relative expression of proprotein convertases in rat ovaries during pregnancy

Background

Proprotein convertases are a family of serine proteinases that are related to bacterial subtilisin and yeast kexin. They are involved in posttranslational processing of the precursors of a vast number of cellular proteins. With the exception of PC1/3, the relative expression levels of the proprotein convertases in the ovary during pregnancy have not been reported. The purpose of this study is to determine by real-time PCR the relative expression levels of all nine proprotein convertases in rat ovaries during pregnancy and at 3 days postpartum.

Methods

RNA was extracted from ovaries at Day 0, 4, 9, 11, 13, 15, 18, and 20 of pregnancy as well as 3 days postpartum. Relative expression levels of Pcsk1, Pcsk2, Furin, Pcsk4, Pcsk5, Pcsk6, Pcsk7, Mbtps1 and Pcsk9 were determined with real-time PCR. Results were reported as fold-change over the level at Day 0 of pregnancy.

Results

Results showed that Pcsk1 and Pcsk6 were upregulated as gestation advanced, in parallel with an observed increase in relaxin transcript. Pcsk2 showed downregulation as gestation advanced, while Pcsk5 showed relatively higher levels in early pregnancy and postpartum, but lower level in mid-pregnancy. On the other hand, Furin, Pcsk4, Pcsk7, Mbtps1 and Pcsk9 showed little change of expression throughout gestation.

Conclusion

PC1/3 (PCSK1) and PACE4 (PCSK6) may play an important role in proprotein processing in the ovary during late pregnancy.

EPR detection of paramagnetic chromium in liver of fish (Anguilla anguilla) treated with dichromate(VI) and associated oxidative stress responses-contribution to elucidation of toxicity mechanisms

The impact of chromium (Cr) on fish health has been the subject of numerous investigations, establishing a wide spectrum of toxicity, attributed particularly to the hexavalent form [Cr(VI)]. However, reports on the simultaneous assessment of Cr toxicity in fish and its toxico-kinetics, namely involving metal speciation, are scarce. Therefore, keeping in view the understanding of the mechanisms of Cr(VI) toxicity, this work intended to detect the formation of paramagnetic Cr species in liver of Anguilla anguilla following short-term dichromate(VI) intraperitoneal treatment (up to 180 min), assessing simultaneously the pro-oxidant properties. The formation of Cr(V) and Cr(III) was examined by electron paramagnetic resonance (EPR), as an innovative approach in the context of fish toxicology, and related with the levels of total Cr. Cr(V) was successfully detected and quantified by EPR spectrometry, showing a transient occurrence, mostly between 15 and 90 min post-injection, with a peak at 30 min. The limitations of EPR methodology towards the detection and quantification of Cr(III) were confirmed. Although Cr(VI) exposure induced the antioxidant system in the eel's liver, the oxidative deterioration of lipids was not prevented. Overall, the results suggested that Cr(V), as a short-lived species, did not appear to be directly and primarily responsible for the cellular damaging effects observed, since stress responses persisted up to the end of exposure regardless Cr(V) drastic decay. Though further research is needed, ROS mediated pathways (suggested by superoxide dismutase and catalase activity induction) and formation of Cr(III) complexes emerged as the most plausible mechanisms involved in Cr(VI) toxicity.

Endogenous retroviruses function as species-specific enhancer elements in the placenta

The mammalian placenta is remarkably distinct between species, suggesting a history of rapid evolutionary diversification¹. To gain insight into the molecular drivers of placental evolution, we compared biochemically predicted enhancers between mouse and rat trophoblast stem cells (TSCs) and find that species-specific enhancers are highly enriched for endogenous retroviruses (ERVs) on a genome-wide level. One of these ERV families, RLTR13D5, contributes hundreds of mouse-specific H3K4me1/H3K27ac-defined enhancers that functionally bind Cdx2, Eomes, and Elf5 - core factors that define the TSC regulatory network. Furthermore, we demonstrate that RLTR13D5 is capable of driving gene expression in rat placental cells. Comparison with other tissues revealed that species-specific ERV enhancer activity is generally restricted to hypomethylated tissues, suggesting that tissues permissive to ERV activity gain access to an otherwise silenced source of regulatory variation. Overall, our results implicate ERV enhancer cooption as a mechanism underlying the striking evolutionary diversification of placental development.

Factors determining the risk of the metabolic syndrome: is there a central role for adiponectin?

BACKGROUND AND OBJECTIVES

The pathogenesis of the metabolic syndrome (MetS) is not well understood. This review is based on the hypothesis that both traditional and emerging risk factors act through adiponectin.

SUBJECTS AND METHODS

We conducted a search of the literature using prominent electronic databases and search terms that included in combination: adiponectin, diet, dietary patterns, exercise, metabolic rate, MetS and testosterone. Articles were restricted to studies conducted on adult humans, reported in English and within the time period 2000-2012.

RESULTS AND CONCLUSIONS

Both traditional and emerging risk factors associated with the MetS show some evidence of exerting their influence through adiponectin. High-quality randomized controlled trials that alter adiponectin levels are required to further corroborate this hypothesis.

Regulatory pathways controlling the endovascular invasive trophoblast cell lineage

Hemochorial placentation is characterized by trophoblast-directed uterine spiral artery remodeling. The rat and human both possess hemochorial placentation and exhibit remarkable similarities regarding the depth of trophoblast invasion and the extent of uterine vascular modification. In vitro and in vivo research methodologies have been established using the rat as an animal model to investigate the extravillous/invasive trophoblast lineage. With these research approaches, two signaling pathways controlling the differentiation and invasion of the trophoblast cell lineage have been identified: i) hypoxia/hypoxia inducible factor and ii) phosphatidylinositol 3-kinase/AKT/Fos like antigen 1. Dissection of these pathways has facilitated identification of fundamental regulators of the invasive trophoblast cell lineage.

A focused microarray for screening rat embryonic stem cell lines

Here, we describe a focused microarray for screening rat embryonic stem cells (ESCs) and provide validation data that this array can distinguish undifferentiated rat ESCs from rat trophoblast stem (TS) cells, rat extraembryonic endoderm cells, mouse embryonic fibroblast feeder cells, and differentiated rat ESCs. Using this tool, genuine rat ESC lines, which have been expanded in a conventional rat ESC medium containing two inhibitors (2i), for example, glycogen synthase kinase 3 (GSK3) and mitogen-activated protein kinase (MEK) inhibitors, and leukemia inhibitory factor, and genuine rat ESCs, which have been expanded in rat ESC medium containing four inhibitors (4i), for example, GSK3, MEK, Alk5, and Rho-associated kinase inhibitors were compared; as were genuine rat ESCs from 4 different strains of rats. Expression of Cdx2, a gene associated with trophoblast determination, was observed in genuine, undifferentiated rat ESCs from 4 strains and from both 2i and 4i ESC derivation medium. This finding is in contrast to undifferentiated mouse ESCs that do not express Cdx2. The rat ESC focused microarray described in this report has utility for rapid screening of rat ESCs. This tool will enable optimization of culture conditions in the future.