Metal transcription factor-1 is involved in hypoxia-dependent regulation of placenta growth factor in trophoblast-derived cells

Zinc promotes cell proliferation via regulating metal-regulatory transcription factor 1 expression and transcriptional activity in pulmonary arterial hypertension

Metal responsive transcription factor 1 (MTF-1) is a zinc-dependent transcription factor involved in the development of pulmonary arterial hypertension (PAH), which is a life-threatening disease characterized by elevated pulmonary artery pressure and pulmonary vascular remodeling. However, little is known about the role and regulatory signaling of MTF-1 in PAH. This study aimed to investigate the effect and mechanism of MTF-1 on the proliferation of pulmonary arterial smooth muscle cells (PASMCs). Several techniques including intracellular-free zinc detected by fluorescent indicator-fluozinc-3-AM, western blot, luciferase reporter, and cell proliferation assay were conducted to perform a comprehensive analysis of MTF-1 in proliferation of PASMCs in PAH. Increased cytosolic zinc was shown in monocrotaline (MCT)-PASMCs and ZnSO₄-treated PASMCs, which led to overexpression and overactivation of MTF-1, followed by the up-regulation of placental growth factor (PlGF). Elevated MTF-1 and PlGF were observed in western blot, and high transcriptional activity of MTF-1 was confirmed by luciferase reporter in ZnSO4-treated cells. Further investigation of cell proliferation revealed a favorable impact of zinc ions on PASMCs proliferation, with the deletion of Mtf-1/Plgf attenuating ZnSO4-induced proliferation. Flow cytometry analysis showed that blockade of PKC signaling inhibited the cell cycle of MCT-PASMCs and ZnSO4-treated PASMCs. The Zinc/PKC/MTF-1/PlGF pathway is involved in the up-regulatory effect on the PASMCs proliferation in the process of PAH. This study provided novel insight into zinc homeostasis in the pathogenesis of PAHs, and the regulation of MTF-1 might be a potential target for therapeutic intervention in PAH.

Hyperglycaemia up-regulates placental growth factor (PlGF) expression and secretion in endothelial cells via suppression of PI3 kinase-Akt signalling and activation of FOXO1

Placenta growth factor (PlGF) is a pro-inflammatory angiogenic mediator that promotes many pathologies including diabetic complications and atherosclerosis. Widespread endothelial dysfunction precedes the onset of these conditions. As very little is known of the mechanism(s) controlling PlGF expression in pathology we investigated the role of hyperglycaemia in the regulation of PlGF production in endothelial cells. Hyperglycaemia stimulated PlGF secretion in cultured primary endothelial cells, which was suppressed by IGF-1-mediated PI3K/Akt activation. Inhibition of PI3K activity resulted in significant PlGF mRNA up-regulation and protein secretion. Similarly, loss or inhibition of Akt activity significantly increased basal PlGF expression and prevented any further PlGF secretion in hyperglycaemia. Conversely, constitutive Akt activation blocked PlGF secretion irrespective of upstream PI3K activity demonstrating that Akt is a central regulator of PlGF expression. Knock-down of the Forkhead box O-1 (FOXO1) transcription factor, which is negatively regulated by Akt, suppressed both basal and hyperglycaemia-induced PlGF secretion, whilst FOXO1 gain-of-function up-regulated PlGF in vitro and in vivo. FOXO1 association to a FOXO binding sequence identified in the PlGF promoter also increased in hyperglycaemia. This study identifies the PI3K/Akt/FOXO1 signalling axis as a key regulator of PlGF expression and unifying pathway by which PlGF may contribute to common disorders characterised by endothelial dysfunction, providing a target for therapy.

The impact of maternal asthma during pregnancy on offspring retinal microvascular structure and its relationship to placental growth factor production in utero

Asthma is a common chronic disease in pregnancy that affects placental function and fetal growth and associated with cardio-metabolic disorders in the offspring but the mechanisms are unknown. This study explored whether maternal asthma in pregnancy is associated with the development of offspring microvascular structure and whether it was related to biomarkers of angiogenesis in utero. Children aged 4 to 6 years, born to either asthmatic mothers (n = 38) or healthy controls (n = 25), had their retinal microvascular structure examined. Maternal plasma PlGF concentrations at 18 and 36 weeks' gestation were measured. There was a significant global difference in all retinal microvascular measures between children of asthmatic mothers relative to controls and increased retinal venular tortuosity in children born to asthmatic mothers (7.1 (95% CI 0.7-13.5); P = .031). A rise in plasma PlGF from 18 to 36 weeks' gestation was observed in the control population which was significantly lower in the asthma group by 190.9 pg/mL. PlGF concentrations were correlated with microvascular structure including arteriolar branching and venular tortuosity. These exploratory findings indicate that exposure to maternal asthma during pregnancy is associated with persistent changes in microvascular structure in childhood that may be driven by alterations to angiogenic mechanisms in utero.

A T > G Mutation in the NR5A2 Gene Is Associated With Litter Size in Hu Sheep Through Upregulation of Promoter Activity by Transcription Factor MTF-1

Nuclear receptor subfamily 5 group A member 2 (NR5A2), also referred to as LRH-1 or FTF, is an orphan nuclear hormone receptor that is involved in regulating embryonic development, ovarian granulosa cell differentiation, gonadal sex differentiation, and steroidogenesis in mammals. However, little is known about how NR5A2 regulates reproduction in sheep. In this study, we amplified the promoter sequence of NR5A2 and determined that its core promoter region ranged from -721 nt to -281 nt. A T > G polymorphism at -700 nt was detected in the core promoter region. Association analysis found that the litter sizes of Hu ewes at their second and average parities with genotype GG (2.20 ± 0.20 and 1.97 ± 0.06, respectively) were significantly higher than those of ewes with genotype TG (1.68 ± 0.10 and 1.74 ± 0.05, respectively) (p < 0.05) and TT (1.67 ± 0.10 and 1.62 ± 0.06, respectively) (p < 0.05). The litter size of Hu ewes at their third parity with genotype GG (2.10 ± 0.10) was significantly higher than that of ewes with genotype TT (1.56 ± 0.12) (p < 0.05). A luciferase assay showed that the -700G allele increased the luciferase activity relative to the -700T allele. Furthermore, the -700T > G polymorphism created a novel binding site for metal-regulatory transcription factor 1 (MTF-1). A competitive electrophoretic mobility shift assay confirmed that MTF-1 specifically bound with the G-type promoter of NR5A2. An overexpression experiment demonstrated that MTF-1 was involved in the alteration of NR5A2 transcription activity and further increased NR5A2 gene mRNA expression. Our findings revealed that the -700T > G polymorphism promoted NR5A2 expression due to the positive effects on NR5A2 gene transcription activity by MTF-1 and thereby increased fecundity in Hu sheep.

New insights into the regulation of placental growth factor gene expression by the transcription factors GCM1 and DLX3 in human placenta

Expression of placental growth factor (PGF) is closely associated with placental perfusion in early pregnancy. PGF is primarily expressed in placental trophoblasts, and its expression decreases in preeclampsia, associated with placental hypoxia. The transcription factors glial cells missing 1 (GCM1) and metal-regulatory transcription factor 1 (MTF1) have been implicated in the regulation of PGF gene expression through regulatory elements upstream and downstream of the PGF transcription start site, respectively. Here, we clarified the mechanism underlying placenta-specific PGF expression. We demonstrate that GCM1 up-regulates PGF expression through three downstream GCM1-binding sites (GBSs) but not a previously reported upstream GBS. Interestingly, we also found that these downstream GBSs also harbor metal-response elements for MTF1. Surprisingly, however, we observed that MTF1 is unlikely to regulate PGF expression in the placenta because knockdown or overexpression of GCM1, but not MTF1, dramatically decreased PGF expression or reversed the suppression of PGF expression under hypoxia, respectively. We also demonstrate that another transcription factor, Distal-less homeobox 3 (DLX3), interacts with the DNA-binding domain and the first transactivation domain of GCM1 and that this interaction inhibits GCM1-mediated PGF expression. Moreover, the GCM1-DLX3 interaction interfered with CREB-binding protein-mediated GCM1 acetylation and activation. In summary, we have identified several GBSs in the PGF promoter that are highly responsive to GCM1, have demonstrated that MTF1 does not significantly regulate PGF expression in placental cells, and provide evidence that DLX3 inhibits GCM1-mediated PGF expression. Our findings revise the mechanism for GCM1- and DLX3-mediated regulation of PGF gene expression.

Micromolar Zinc in Annexin A5 Anticoagulation as a Potential Remedy for RPRGL3-Associated Recurrent Pregnancy Loss

Deficient expression of the placental anticoagulant annexin A5 (ANXA5) has been associated with thrombophilia-related pregnancy complications and ultimately with recurrent pregnancy loss (RPL). Carrier status of M2/ANXA5 ( RPRGL3), common ANXA5 promoter variant, has been identified as genetic cause of reduced ANXA5 levels and proposed as biomarker for successful anticoagulant treatment of RPL women. A murine model of AnxA5 loss of function displayed characteristic placental pathology and fetal loss that was alleviated through anticoagulant intervention. This study identified an alternative means of supplementing anticoagulation, through elevated ANXA5 expression. Physiological micromolar Zn²⁺ stimulated ANXA5 transcription, raising ANXA5 protein expression and surface abundance on BeWo and human umbilical vein endothelial cells (HUVEC), thus resulting in prolonged coagulation times. Zn²-fed AnxA5 functionally deficient pregnant mice showed a trend to increase litter size when primiparous that grew comparable to wild-type progeny in subsequent pregnancies. Elevated AnxA5 signal upon Zn²⁺ treatment was confirmed in murine placentae. Micromolar Zn²⁺ stimulated ANXA5 expression in cell culture directly and alleviated RPL in AnxA5 genetically deficient mice, without notable toxicity effects.

An in vitro inflammation model to study the Nrf2 and NF-κB crosstalk in presence of ferulic acid as modulator

The aim of this study was to evaluate the crosstalk between Nrf2 and NF-κB signaling pathways and to explore the modulating activity actuated by ferulic acid. In the inflammation process, a key player is the nuclear factor-κB (NF-κB) transcription factor pathway. On the contrary, the activation of Nrf2 inhibits inflammation and impairs degenerative disease providing an interface between redox and anti-inflammatory responses. Recent studies have demonstrated that protein phosphorylation of IKK complex is a potential mechanism for the activation of both Nrf2 and NF-κB pathways. The IKK complex is as an integration point for signals emanating from these different pathways. In this study, we demonstrated that ferulic acid is able to regulate NF-κB and Nrf2 activities. Interestingly, we showed that ferulic acid mimics the potent IKK inhibitor such as BMS, down-regulating the NF-κB response, TAK 1 activation and turning off Nrf2 activities in LPS-stimulated RAW 264.7 cells. Immunoblot data showed that the release of Nrf2 from Keap1 is maintained at low levels also in the presence of LPS stimulus. Nrf2 controls the expression of many antioxidant and detoxification genes, by binding to antioxidant response elements (AREs) that are commonly found in the promoter region of antioxidant (and other) genes. We demonstrated that in the pARE-Luc transfected cells the pre-treatment with FA significantly reduced LPS-induced (p<0.01) and BMS-induced (p<0.01) transcriptional activities. Analysis of well-known Nrf2 transcriptional targets showed that mRNAs expression of Nrf2-dependent antioxidant and phase II enzymes such as dehydrogenase quinone1 (NQO1) and glutathione S-transferase A2 (GSTA2) were up-regulated by BMS and significantly increase more by association with LPS, but are down-regulated in the presence of FA. Interestingly, cells depleted of Keap1 showed increased response of the Nrf2 transcriptional activity also in the presence of FA, strongly suggesting its modulating role in Keap1-Nrf2 signaling pathway.

Dlx3 and GCM-1 functionally coordinate the regulation of placental growth factor in human trophoblast-derived cells

Placental growth factor (PGF) is abundantly expressed by trophoblast cells within human placentae and is important for trophoblast development and placental vascularization. Circulating maternal serum levels of PGF are dynamically upregulated across gestation in normal pregnancies, whereas low circulating levels and placental production of PGF have been implicated in the pathogenesis of preeclampsia and other gestational diseases. However, the underlying molecular mechanism of regulating PGF expression in the human placenta remains poorly understood. In this study, we demonstrated that transcription factors Distal-less 3 (DLX3) and Glial cell missing-1 (GCM1) were both sufficient and required for PGF expression in human trophoblast-derived cells by overexpression and knockdown approaches. Surprisingly, while DLX3 and GCM1 were both positive regulators of PGF, co-overexpression of DLX3 and GCM1 led to an antagonist effect on PGF expression on the endogenous gene and a luciferase reporter. Further, deletion and site-directed mutagenesis studies identified a novel regulatory element on the PGF promoter mediating both DLX3- and GCM1-dependent PGF expression. This regulatory region was also found to be essential for the basal activity of the PGF promoter. Finally, Chromatin-immunoprecipitation (ChIP) assays revealed colocalization of DLX3 and GCM1 at the identified regulatory region on the PGF promoter. Taken together, our studies provide important insights into intrinsic regulation of human placental PGF expression through the functional coordination of DLX3 and GCM1, and are likely to further the understanding of pathogenesis of PGF dysregulation in preeclampsia and other disease conditions.

Molecular Mechanisms of Preeclampsia

Preeclampsia is a pregnancy-specific disease characterized by new onset hypertension and proteinuria after 20 wk of gestation. It is a leading cause of maternal and fetal morbidity and mortality worldwide. Exciting discoveries in the last decade have contributed to a better understanding of the molecular basis of this disease. Epidemiological, experimental, and therapeutic studies from several laboratories have provided compelling evidence that an antiangiogenic state owing to alterations in circulating angiogenic factors leads to preeclampsia. In this review, we highlight the role of key circulating antiangiogenic factors as pathogenic biomarkers and in the development of novel therapies for preeclampsia.

Erythropoietin-mediated expression of placenta growth factor is regulated via activation of hypoxia-inducible factor-1α and post-transcriptionally by miR-214 in sickle cell disease

Placental growth factor (PlGF) plays an important role in various pathological conditions and diseases such as inflammation, cancer, atherosclerosis and sickle cell disease (SCD). Abnormally high PlGF levels in SCD patients are associated with increased inflammation and pulmonary hypertension (PHT) and reactive airway disease; however, the transcriptional and post-transcriptional mechanisms regulating PlGF expression are not well defined. Herein, we show that treatment of human erythroid cells and colony forming units with erythropoietin (EPO) increased PlGF expression. Our studies showed EPO-mediated activation of HIF-1α led to subsequent binding of HIF-1α to hypoxia response elements (HREs) within the PlGF promoter, as demonstrated by luciferase transcription reporter assays and ChIP analysis of the endogenous gene. Additionally, we showed miR-214 post-transcriptionally regulated the expression of PlGF as demonstrated by luciferase reporter assays using wild-type (wt) and mutant PlGF-3'-UTR constructs. Furthermore, synthesis of miR-214, located in an intron of DNM3 (dynamin 3), was transcriptionally regulated by transcription factors, peroxisome proliferator-activated receptor-α (PPARα) and hypoxia-inducible factor-1α (HIF-1α). These results were corroborated in vivo wherein plasma from SCD patients and lung tissues from sickle mice showed an inverse correlation between PlGF and miR-214 levels. Finally, we observed that miR-214 expression could be induced by fenofibrate, a Food and Drug Administration (FDA) approved PPARα agonist, thus revealing a potential therapeutic approach for reduction in PlGF levels by increasing miR-214 transcription. This strategy has potential clinical implications for several pathological conditions including SCD.

Expression of placenta growth factor, soluble fms-like tyrosine kinase-1, metal-responsive transcription factor-1, heme oxygenase 1 and hypoxia inducible factor-1α mRNAs in pre-eclampsia placenta and the effect of pre-eclampsia sera on their expression of choriocarcinoma cells

AIM

We studied the effect of pre-eclampsia sera on the expression of placenta growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), metal-responsive transcription factor-1 (MTF-1), heme oxygenase 1 (HO-1) and hypoxia inducible factor-1α (HIF-1α) mRNAs in JEG-3 cells (trophoblast-derived cells) and placenta from pre-eclampsia patients to investigate pre-eclampsia pathophysiology.

MATERIAL AND METHODS

Placenta and serum samples were taken from pre-eclampsia and normal pregnancy patients. JEG-3 cells were cultured with pre-eclampsia and normal pregnant sera in 24-well tissue culture plates. RNA was purified from placental trophoblast cells and JEG-3 cells 24 h after incubation. The expression of mRNA was measured using real-time polymerase chain reaction.

RESULTS

The expression of sFlt-1 mRNA increased, and that of PlGF and HO-1 mRNA decreased in JEG-3 cells after incubation with pre-eclampsia sera. The expression of PlGF mRNA decreased, and that of sFlt-1mRNA increased in pre-eclampsia placenta. The expression of MTF-1 and HO-1 mRNA decreased. A correlation was found between PlGF mRNA expression and the expression of MTF-1 and HIF-1α mRNA. A correlation between sFlt-1 and HIF-1α mRNA expression was also found.

CONCLUSION

Changes in PlGF mRNA expression in pre-eclampsia placenta may relate to serum factors and the expression of MTF-1 and HIF-α mRNA. Changes in sFlt-1mRNA expression may relate to serum factors and the expression of HIF-α mRNA. We suggest that serum factors play a role in PlGF and sFlt-1 expression in pre-eclampsia placenta.

PlGF mediates neutrophil elastase-induced airway epithelial cell apoptosis and emphysema

Background

Chronic pulmonary obstructive disease (COPD) has become the fourth leading cause of death worldwide. Cigarette smoking induces neutrophil elastase (NE) and contributes to COPD, but the detailed mechanisms involved are not fully established. In an animal model of pulmonary emphysema, there are increased expressions of placenta growth factor (PlGF) and lung epithelial (LE) cell apoptosis. This study hypothesized that excessive NE may up-regulate PlGF and that PlGF-induced LE apoptosis mediates the pathogenesis of pulmonary emphysema.

Methods

Human bronchial epithelial cells, BEAS-2B, and primary mouse type II alveolar epithelial cells were treated with NE. The PlGF promoter activity was examined by luciferase activity assay, while PlGF expression and secretion were evaluated by RT-PCR, Western blotting, and ELISA. Both cell lines were treated with PlGF to evaluate its effects and the downstream signaling pathways leading to LE cell apoptosis. PlGF knockout and wild-type mice were instilled with NE to determine the roles of PlGF and its downstream molecules in NE-promoted mice pulmonary apoptosis and emphysema phenotype.

Results

The transcriptional factor, early growth response gene-1, was involved in the NE-promoted PlGF promoter activity, and the expression and secretion of PlGF mRNA and protein in LE cells. PlGF-induced LE cell apoptosis and NE-induced mice pulmonary apoptosis and emphysema were mediated by the downstream c-Jun N-terminal kinase (JNK) and protein kinase C (PKC)δ signaling pathways.

Conclusion

The NE-PlGF-JNK/PKCδ pathway contributes to the pathogenesis of LE cell apoptosis and emphysema. PlGF and its downstream signaling molecules may be potential therapeutic targets for COPD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0106-1) contains supplementary material, which is available to authorized users.

Placenta growth factor mediates angiogenesis in hypoxic pulmonary hypertension

Our previous studies have proved that hypoxia enhances the 15-lipoxygenase (15-LO) expression and increases endogenous 15-hydroxyeicosatetraenoic acid (15-HETE) production to promote pulmonary vascular remodeling and angiogenesis, while the mechanisms of how hypoxia regulates 15-LO expression in endothelium is still unknown. As placenta growth factor (PlGF) promotes pathological angiogenesis by acting on the growth, migration and survival of endothelial cells, there may be some connections between PlGF and 15-LO in hypoxia induced endothelial cells proliferation. In this study, we performed immunohistochemistry, pulmonary artery endothelial cells migration and bromodeoxyuridine incorporation to determine the role of PlGF in pulmonary remodeling induced by hypoxia. Our results showed that hypoxia up-regulated PlGF expression, which was mediated by 15-LO/15-HETE pathway. Furthermore, we found that PlGF had a positive feedback regulation with 15-LO expression and 15-HETE generation. The interaction in hypoxia between 15-HETE and PlGF created a PlGF-15-LO-15-HETE loop, leading to endothelial dysfunction. Thus, these findings suggest a new therapeutic agent in combination with the blockade of PlGF as well as 15-LO in hypoxic pulmonary hypertension.

The herpes simplex virus-1 transactivator infected cell protein-4 drives VEGF-A dependent neovascularization

Herpes simplex virus-1 (HSV-1) causes lifelong infection affecting between 50 and 90% of the global population. In addition to causing dermal lesions, HSV-1 is a leading cause of blindness resulting from recurrent corneal infection. Corneal disease is characterized by loss of corneal immunologic privilege and extensive neovascularization driven by vascular endothelial growth factor-A (VEGF-A). In the current study, we identify HSV-1 infected cells as the dominant source of VEGF-A during acute infection, and VEGF-A transcription did not require TLR signaling or MAP kinase activation. Rather than being an innate response to the pathogen, VEGF-A transcription was directly activated by the HSV-1 encoded immediate early transcription factor, ICP4. ICP4 bound the proximal human VEGF-A promoter and was sufficient to promote transcription. Transcriptional activation also required cis GC-box elements common to the VEGF-A promoter and HSV-1 early genes. Our results suggest that the neovascularization characteristic of ocular HSV-1 disease is a direct result of HSV-1's major transcriptional regulator, ICP4, and similarities between the VEGF-A promoter and those of HSV-1 early genes.

Herpes simplex virus-type 1 is the leading cause of infectious corneal blindness in the industrialized world. Most of the morbidity associated with the virus is due to the host response to episodic reactivation of latent virus. Corneal immunologic privilege is associated with a number of factors including the absence of blood and lymphatic vessels. Conversely, corneal hem (blood)- and lymph-angiogenesis driven by inflammation correlate with the loss of privilege. Neovascularization is a common phenomenon in HSV-1 keratitis that correlates with poor prognosis. We have previously discovered HSV-1 elicits corneal lymphangiogenesis through a unique mechanism involving vascular endothelial growth factor (VEGF)-A independent of that described for other insults including transplantation or bacterial infection. However, the viral-encoded product(s) that elicit host production of VEGF-A is(are) unknown. In this paper, we have identified infected cell protein-4 (ICP4) as the primary virus-encoded product that drives VEGF-A expression. As VEGF-A is involved in driving neovascularization associated with tumor growth and metastasis, proteins that influence transcriptional regulation of VEGF-A may be useful in the development of adjunct therapy for such disparate diseases as cancer and HSV-1 keratitis.

Nitric oxide generation affects pro- and anti-angiogenic growth factor expression in primary human trophoblast

OBJECTIVES

Preeclampsia is associated with reduced trophoblast placenta growth factor (PGF) expression, elevated soluble fms-like tyrosine kinase-1 (sFlt-1) and decreased bioactivity of nitric oxide (NO). Elevated sFlt-1 reduces bio-availability of PGF and vascular endothelial growth factor (VEGF) leading to maternal endothelial dysfunction. Although NO can regulate gene expression, its ability to regulate trophoblast expression of angiogenic growth factors is not known.

STUDY DESIGN

Human primary term trophoblast and JEG-3 choriocarcinoma cells were cultured under 21%O(2) or 1%O(2) conditions in the presence or absence of NO donor (SNP) or inhibitor (L-NAME). Effects on PGF, VEGF and Flt-1 isoform mRNA expression were determined by quantitative real-time PCR. Changes in expression of soluble protein isoforms of FLT-1 was monitored by ELISA.

RESULTS

Hypoxia decreased PGF mRNA but increased VEGF, sFlt-1 and Flt-1 mRNA expression in trophoblast. Generation of NO in trophoblast under 1%O(2) culture conditions significantly reversed sFlt-1 mRNA and protein expression, independent of mFlt-1. Conversely NO generation in hypoxic trophoblast increased VEGF and PGF mRNA expression.

CONCLUSIONS

NO production in primary human trophoblast cultures had divergent effects on pro-angiogenic (PGF, VEGF) versus anti-angiogenic (sFlt-1) mRNA expression, resulting in an enhanced pro-angiogenic gene expression environment in vitro.

Prenatal stretching exercise and autonomic responses: preliminary data and a model for reducing preeclampsia

PURPOSE

Preeclampsia is a leading cause of perinatal mortality and morbidity, and it increases maternal risk for future cardiovascular disease. The purpose of the study was to explore the relationships among stretching exercise, autonomic cardiac response, and the development of preeclampsia.

DESIGN

Secondary data analysis.

METHODS

Heart rate and pulse pressure were longitudinally examined in this secondary data analysis among women who engaged in stretching exercise daily from 18 weeks of gestation to the end of pregnancy compared with women who did walking exercise daily during the same time period. A total of 124 women were randomized to either stretching (n=60) or walking (n=64) in the parent study.

FINDINGS

Heart rates in the stretching group were consistently lower than those in the walking group.

CONCLUSIONS

Based on the results of this secondary data analyses, a physiologic framework for possible beneficial effects of stretching exercise by enhancing autonomic responses on reducing risks for preeclampsia is proposed and discussed.

CLINICAL RELEVANCE

If the protective effect is established, stretching exercise can be translated into nursing intervention for prenatal care.

Comparative analysis of MTF-1 binding sites between human and mouse

MTF-1 is a crucial transcription factor involved in the cellular response to heavy-metal load and other stresses by specifically binding to metal response elements (MREs). Thus far only a handful of direct target genes are known for this transcription factor, limiting our understanding of the biological network it governs. In this article we try to employ a computational strategy based on the generation of literature-based positional weight matrices (PWM) and log-likelihood scoring of the candidate binding sites (BSs) for identification of direct targets of the transcription factor MTF-1 in human and mouse. Through comparisons, we explore the conservation and unique characteristics between two species. Our results show that the numbers of MREs differ dramatically between species and their positions relative to their cognate promoter is also flexible. Importantly, we identify a set of target genes generally well conserved between human and mouse. Finally, by combining expression analysis we provide two putative targets (HMGCR and CYP51A), which regulate lipid metabolism conserved in human and mouse. Overall, interspecies comparison from our study may provide some valuable information for further studying human Wilson disease (WD) using mouse model systems.

Differential regulation of human PlGF gene expression in trophoblast and nontrophoblast cells by oxygen tension

OBJECTIVE

To determine the mechanism for differential effects of low oxygen tension on human PlGF gene transcription in trophoblast and nontrophoblast cells.

STUDY DESIGN

Human PlGF reporter clones and real-time RT-PCR were used to compare the effects of hypoxia on gene transcription in human trophoblast and nontrophoblast cell lines. Overexpression of HIF-1alpha, inhibition of HIF-1 function and biochemical assessments of HIF-1 co-factor interactions were used to characterize hypoxia response mechanisms regulating PlGF transcription.

RESULTS

PlGF transcription is specifically inhibited by low oxygen tension in trophoblast but is induced in some nontrophoblast cells. Overexpression of HIF-1alpha in normoxic cells or inhibition of HIF-1 function in hypoxic cells did not significantly alter transcription patterns of the PlGF gene in either cell type.

CONCLUSIONS

These results suggest that transcriptional repression of PlGF gene expression occurs in human trophoblast exposed to low oxygen tension but that PlGF transcription is stimulated in certain hypoxic nontrophoblast cells. However, regulation of PlGF transcription is not mediated by functional HIF-1 activity in either cell type.