Context: Placental angiogenesis contributes to the pathogenesis of preeclampsia (PE) that affects 5–8% of all human pregnancies. MicroRNA (miRNA) are a class of noncoding 21- to 25-nucleotide RNA that negatively regulate gene expression posttranscriptionly. Objective: The aim of this study was to test the hypothesis that miRNA are differentially expressed in healthy term and PE placentas and a subclass of angiogenesis-associated miRNA are increased by PE. Design: Total miRNA were extracted from villous placental tissues from healthy term and severe preeclamptic pregnancies. Differential miRNA expression was analyzed by microarray and real-time quantitative PCR. Angiogenesis-associated miRNA were analyzed by target prediction databases. In situ hybridization was used to localize miRNA. Target verification was performed by transfection of miRNA precursors or antagomirs into endothelial and BeWo cells and luciferase reporter assays. Results: Three highly expressed miRNA (miR-17, -20a, and -20b) were found significantly increased in PE compared with healthy term placentas (n = 10 per group). They target on the same group of genes important for angiogenesis. miR-20b was expressed primarily in villous syncytiotrophoblasts in term placenta. Overexpression or inhibition of miR-20b differentially regulated mRNA expression of those genes in endothelial vs. trophoblast cells. Luciferase reporter assay showed that miR-20b targets EPHB4 and ephrin-B2 that have been shown to be critical for early human placental development. Placental ephrin-B2 mRNA was significantly down-regulated in PE compared with normotensive pregnancies. Conclusion: miR-17, miR-20a, and miR-20b are differentially regulated in human placentas by PE. They regulate EPHB4 and ephrin-B2 expression in trophoblast and endothelial cells via the same “seed” sequence, suggesting their roles in early placental development.

MicroRNAs are a class of noncoding small RNAs that regulate the expression of nearly 30% of all the human genes and participate in all fundamental cel

Normal pregnancy is associated with dramatic increases in uterine blood flow to facilitate the bidirectional maternal–fetal exchanges of respiratory gases and to provide sole nutrient support for fetal growth and survival. The mechanism(s) underlying pregnancy-associated uterine vasodilation remain incompletely understood, but this is associated with elevated estrogens, which stimulate specific estrogen receptor (ER)-dependent vasodilator production in the uterine artery (UA). The classical ERs (ERα and ERβ) and the plasma-bound G protein-coupled ER (GPR30/GPER) are expressed in UA endothelial cells and smooth muscle cells, mediating the vasodilatory effects of estrogens through genomic and/or nongenomic pathways that are likely epigenetically modified. The activation of these three ERs by estrogens enhances the endothelial production of nitric oxide (NO), which has been shown to play a key role in uterine vasodilation during pregnancy. However, the local blockade of NO biosynthesis only partially attenuates estrogen-induced and pregnancy-associated uterine vasodilation, suggesting that mechanisms other than NO exist to mediate uterine vasodilation. In this review, we summarize the literature on the role of NO in ER-mediated mechanisms controlling estrogen-induced and pregnancy-associated uterine vasodilation and our recent work on a “new” UA vasodilator hydrogen sulfide (H₂S) that has dramatically changed our view of how estrogens regulate uterine vasodilation in pregnancy.

On vascular endothelial growth factor (VEGF) stimulation, both VEGF R1 and R2 receptors were phosphorylated in ovine fetoplacental artery endothelial (oFPAE) cells. Treatment with VEGF stimulated both time- and dose-dependent activation of ERK2/1 in oFPAE cells. VEGF-induced ERK2/1 activation was mediated by VEGFR2, but not VEGFR1, and was linked to intracellular calcium, protein kinase C, and Raf-1. VEGF stimulated oFPAE cell proliferation, migration, and tube formation in vitro. Blockade of ERK2/1 pathway attenuated VEGF-induced cell proliferation and tube formation but failed to inhibit migration in oFPAE cells. Disruption of caveolae by cholesterol depletion with methyl-β-cyclodextrin or by down-regulation of its structural protein caveolin-1 blunted VEGF-induced ERK2/1 activation, proliferation, and tube formation in oFPAE cells, indicating an essential role of integral caveolae in these VEGF-induced responses. Adenoviral overexpression of caveolin-1 and addition of a caveolin scaffolding domain peptide also inhibited VEGF-stimulated ERK2/1 activation, cell proliferation, and tube formation in oFPAE cells. Furthermore, molecules comprising the ERK2/1 signaling module, including VEGFR2, protein kinase Cα, Raf-1, MAPK kinase 1/2, and ERK2/1, resided with caveolin-1 in caveolae. VEGF transiently stimulated ERK2/1 activation in the caveolae similarly as in intact cells. Caveolae disruption greatly diminished ERK2/1 activation by VEGF in oFPAE cell caveolae. We conclude that caveolae function as a platform for compartmentalizing the VEGF-induced ERK2/1 signaling module. Caveolin-1 and caveolae play a paradoxical role in regulating VEGF-induced ERK2/1 activation and in vitro angiogenesis as evidenced by the similar inhibitory effects of down-regulation and overexpression of caveolin-1 and disruption of caveolae in oFPAE cells.

Summary Sentence. Augmented hydrogen sulfide biosynthesis via upregulating endothelium and smooth muscle cystathionine β-synthase expression plays a role in pr