RESUMO
OBJECTIVE: Regulation of fetoplacental blood flow is likely mediated by factors such as prostanoids. Estrogen and its receptors affect prostanoid biosynthesis. Previously, we demonstrated that villous endothelial cells express estrogen receptor-beta (ESR2), and we sought to determine its role in the mediation of fetoplacental vascular function. STUDY DESIGN: Villous endothelial cells from uncomplicated pregnancies were isolated, cultured, and treated with estrogen. RNA interference, real-time polymerase chain reaction, Western blotting, and enzyme immunoassays were performed. RESULTS: Cyclooxygenase-2 (COX-2) expression levels were not altered consistently by estrogen. RNA interference of ESR2 led to a concomitant decrease in COX-2 messenger RNA (P < .0001) and protein (P < .05) in the presence and absence of estradiol. ESR2 knock-down also led to diminished prostacyclin and thromboxane concentrations in the absence of estradiol (P < .005). CONCLUSION: ESR2 mediates COX-2 expression levels and both prostacyclin and thromboxane concentrations in the basal state, which suggests the possibility of ligand-independent regulation of COX-2 activity and prostaglandin H2 substrate availability. Further investigation regarding ESR2 regulation of prostanoid biosynthesis and its effects on the fetoplacental vasculature is warranted.
Assuntos
Ciclo-Oxigenase 2/biossíntese , Células Endoteliais/metabolismo , Receptor beta de Estrogênio/fisiologia , Placenta/citologia , Prostaglandinas/biossíntese , Células Cultivadas , Epoprostenol/análise , Epoprostenol/biossíntese , Feminino , Humanos , Placenta/irrigação sanguínea , Prostaglandinas/análise , Tromboxanos/análise , Tromboxanos/biossínteseRESUMO
To date, 10 promoters were reported to regulate the expression of the human aromatase (CYP19) gene, giving rise to transcripts with an identical coding region but tissue-specific first exons comprising unique 5'-untranslated regions. We describe the identification and characterization of a new CYP19 exon I, designated exon I.8, in a 5'-rapid amplification of complementary DNA ends-generated library of human THP-1 monocytic cells. A construct containing exon I.8 and its 5'-flanking sequence was sufficient to drive transcription in THP-1 cells. This novel promoter was located approximately 2-kb upstream of promoter I.4 and approximately 75-kb upstream of the common splice junction. We detected several I.8-containing splice variants, 2 of which also contained a sequence from exon I.4. Analysis of human tissues revealed a unique pattern of promoter I.8 usage. The placenta contained the highest level of I.8-specific transcripts. This work underscores the complexity of the mechanisms that regulate normal and pathologic aromatase expression.