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Preeclampsia (PE) is a common human-specific pregnancy disorder defined by hypertension and proteinuria during gestation and responsible for maternal and fetal morbimortality. STOX1, encoding a transcription factor, was the first gene associated with PE as identified by positional cloning approaches. Its overexpression in choriocarcinoma cells mimics the transcriptional consequences of PE in the human placenta. Here, we created transgenic mouse strains overexpressing human STOX1. Wild-type female mice crossed with transgenic male mice reproduce accurately the symptoms of severe PE: gestational hypertension, proteinuria, and elevated plasma levels of soluble fms-like tyrosine kinase 1 and soluble endoglin. Placental and kidney histology were altered. Symptoms were prevented or alleviated by aspirin treatment. STOX1-overexpressing mice constitute a unique model for studying PE, allow testing therapeutic approaches, and assessing the long-term effects of the preeclamptic syndrome.

The airways of mice deficient in the cAMP phosphodiesterase PDE4D gene are refractory to muscarinic cholinergic stimulation. This study was undertaken to determine whether altered smooth muscle contractility causes the PDE4D-/- phenotype. A major disruption in contractility was observed in isolated PDE4D-/- tracheas, with a 60% reduction in maximal tension and a fivefold decrease in sensitivity to muscarinic cholinergic agonists. Conversely, responses to KCl or arginine vasopressin were unaffected. PDE4D is the predominant PDE4 form in tracheal extracts and PDE4D mRNA is expressed in smooth muscle where muscarinic binding sites are most abundant. Cyclic AMP accumulation in response to acute G(s)alpha-coupled receptor stimulation was increased up to fourfold in the airway of PDE4D-/- mice when compared with wild-type. This increase in cAMP was associated with an increased sensitivity to PGE2-induced relaxation of the PDE4D-/-tracheas. Furthermore, a blockade of prostanoid accumulation in PDE4D-/- tracheas restored the response to muscarinic cholinergic stimulation in vitro and in vivo. These results demonstrate that PDE4D plays a key role in balancing relaxant and contracting cues in airway smooth muscle, suggesting that natural mutations in the PDE4D gene have profound effects on airway tone.

Intrauterine infection is a major cause of spontaneous preterm birth. Amniotic epithelial cells represent the first line of defense against intra-amniotic bacteria. We hypothesize that this epithelial cell barrier is able to recognize and respond to pathogens through the function of TLRs, which are crucial regulators of the innate immune system. In this study, we describe the expression of transcripts for TLR1–TLR10 in human amniotic epithelial cells. We show that amniotic epithelial cells express functional TLR5, TLR6/2, and TLR4. Activation by TLR5 and TLR6/2 agonists produces IL-6 and IL-8, concomitantly with the activation of NF-κB signaling pathway, matrix metalloproteinase-9 induction, and PTGS2 expression. In contrast, TLR4 activation reduced amniotic epithelial cell viability and induced cell apoptosis evidenced by an elevated Bax/Bcl-2 ratio and cleavage of caspase-3. These data suggest specific TLR-mediated functions in human amniotic epithelial cells for initiating different immune responses, which ultimately may lead to preterm birth.

We have previously used cyclic nucleotide-gated (CNG) channels as sensors to measure cAMP signals in human embryonic kidney (HEK)-293 cells. We found that prostaglandin E(1) (PGE(1)) triggered transient increases in cAMP concentration near the plasma membrane, whereas total cAMP levels rose to a steady plateau over the same time course. In addition, we presented evidence that the decline in the near-membrane cAMP levels was due primarily to a PGE(1)-induced stimulation of phosphodiesterase (PDE) activity, and that the differences between near-membrane and total cAMP levels were largely due to diffusional barriers and differential PDE activity. Here, we examine the mechanisms regulating transient, near-membrane cAMP signals. We observed that 5-min stimulation of HEK-293 cells with prostaglandins triggered a two- to threefold increase in PDE4 activity. Extracellular application of H89 (a PKA inhibitor) inhibited stimulation of PDE4 activity. Similarly, when we used CNG channels to monitor cAMP signals we found that both extracellular and intracellular (via the whole-cell patch pipette) application of H89, or the highly selective PKA inhibitor, PKI, prevented the decline in prostaglandin-induced responses. Following pretreatment with rolipram (a PDE4 inhibitor), H89 had little or no effect on near-membrane or total cAMP levels. Furthermore, disrupting the subcellular localization of PKA with the A-kinase anchoring protein (AKAP) disruptor Ht31 prevented the decline in the transient response. Based on these data we developed a plausible kinetic model that describes prostaglandin-induced cAMP signals. This model has allowed us to quantitatively demonstrate the importance of PKA-mediated stimulation of PDE4 activity in shaping near-membrane cAMP signals.

In this review, we comprehensively present the function of epigenetic regulations in normal placental development as well as in a prominent disease of placental origin, preeclampsia (PE). We describe current progress concerning the impact of DNA methylation, non-coding RNA (with a special emphasis on long non-coding RNA (lncRNA) and microRNA (miRNA)) and more marginally histone post-translational modifications, in the processes leading to normal and abnormal placental function. We also explore the potential use of epigenetic marks circulating in the maternal blood flow as putative biomarkers able to prognosticate the onset of PE, as well as classifying it according to its severity. The correlation between epigenetic marks and impacts on gene expression is systematically evaluated for the different epigenetic marks analyzed.