Thromboxane A2 Receptor Research Articles

МикроРНК и гены, связанные с артериальной гипертензией

It was identified 128 genes involved in the development of arterial hypertension and binding there mRNAs with miRNAs was studied. It was found 189 binding sites for 82 miRNAs. The changes in expression of 25 microRNAs which were found their target genes were found. From thus, 48 binding sites are located in the CDS, 18 - in the 5'UTR and 122 - in the 3'UTR. Some miRNAs have multiple binding sites with mRNA of genes participating in the development of arterial hypertension. miR-1273e has three binding sites with F11R gene mRNA, miR-466 - five binding sites with CD36 gene mRNA and six binding sites with MYADM gene mRNA, miR-574-5p has nine binding sites with IGF1 gene mRNA, miR-3960 - five sites with ADRB1 gene mRNA and four sites for PDE4D gene mRNA, miR-762 - four binding sites with STK39 gene mRNA. miR-619-5p binds with CACNB2 and CD36 genes mRNA with ΔG/ΔGm value equal to 100%, miR-3960, miR-1273e, miR-1273g-3p, miR-5095, miR-3665, miR-1273f binds with ADRB1, BMPR2, GSTM3, F11R, ICAM1, IGF1, LEP, MYADM, NEDD4L, TBXA2R genes with ΔG/ΔGm value equal to 98%. There was studied the binding of miRNAs with mRNAs of genes, participating in the development of arterial hypertension. It was identified 128 genes, participating in the development of arterial hypertension. It was found changes in expression of 25 microRNAs which were found their target genes in arterial hypertension. In mRNAs of genes involved in the development of arterial hypertension, it was identified 189 binding sites for 82 miRNAs. From thus, 48 binding sites are located in the CDS, 18 are located in the 5'UTR and 122 are located in the 3'UTR. Some miRNAs has multiple binding sites with mRNAs of genes, participating in the development of arterial hypertension. miR-1273e has three binding sites with mRNA of F11R, miR-466 has five binding sites with mRNA of CD36 gene and six binding sites with mRNA of MYADM gene, miR-574-5p has nine binding sites with mRNA of IGF1 gene, miR-3960 has five binding sites with mRNA of ADRB1 gene and four sites for mRNA of PDE4D gene, miR-762 has four binding sites with mRNA of STK39 gene. miR-619-5p binds with CACNB2 and CD36 genes, with ΔG/ΔGm value equal to 100%, miR-3960, miR-1273e, miR-1273g-3p, miR-5095, miR-3665, miR-1273f binds with ADRB1, BMPR2, GSTM3, F11R, ICAM1, IGF1, LEP, MYADM, NEDD4L, TBXA2R genes with ΔG/ΔGm value equal to 98%. The highest ΔG value is observed in the interaction of miR-6089 with mRNA of TGFB1 gene and equal to -136 kJ/mole. miR-762 binds with mRNA of STK39 gene with a ΔG value equal to -132 kJ/mole. miR-466 has four target genes: CD36, F11R, MYADM, ICAM1 with energy value from -104 kJ/mole to -108 kJ/mole and the ΔG/ΔGm value from 89% to 93% of the maximum free binding energy in miR-466-3p with the mRNA equal to -108 kJ/mole. miR-619-5p has 10 target genes: BMPR2, CACNB2, CD36, ECE1, F11R, GSTM3, LEP, MTHFR, MYADM, ROCK2 with a binding energy value from -110 kJ/mole to -119 kJ/mole and the ΔG/ΔGm value from 91% to 100% of the maximum free binding energy. Each of the target genes for miRNAs and each miRNA can significantly alter the rate of development of arterial hypertension.

Alterations of the Purinergic Regulation in Mesenteric Arteries of Pannexin-1-Knockout Mice

Pannexin 1 (Panx1) forms plasma membrane channels that release ATP, an important vascular tone regulator. However, despite the abundant expression of Panx1 in the vascular system, its effects on smooth muscle contraction are not evident in all arteries. In this study, we tested the hypothesis that the functional consequences of Panx1 deficiency can be masked by the augmented action of ATP secreted in a Panx1-independent way. Experiments were performed on small mesenteric arteries obtained from Panx1-knockout (Panx1–/–) and C57Bl/6 (Panx1+/+) male mice using wire myography of endothelium-denuded arterial preparations and reverse-transcription quantitative PCR techniques. Arterial contractile responses to phenylephrine did not differ in two experimental groups. Ecto-ATPase inhibitor ARL67156 (100 μM) potentiated the responses to phenylephrine in Panx1+/+ but not in Panx1–/–, while ARL67156 did not affect the contractile responses to the thromboxane A2 receptor agonist in any of the two groups. Contractile responses to exogenous ATP (10 μM) were smaller in Panx1+/+ than in Panx1–/– mice. By contrast, NTPDase1 mRNA content was higher in Panx1+/+ than in Panx1–/– mice. These results suggest that ATP released from smooth muscle cells through Panx1 channels can potentiate contractile responses of murine mesenteric arteries upon activation of α1-adrenoceptors. In Panx1–/– mice an increased arterial ATP sensitivity and diminished NTPDase1 activity may augment the contractile effects of Panx1-independent ATP.

Possible mechanisms of diverse spaceflight effects on endothelial function in different vascular beds

Possible mechanisms of diverse spaceflight effects on endothelial function in different vascular beds

Impairment of amyloid precursor protein alpha-processing in cerebral microvessels of type 1 diabetic mice

The mechanisms underlying dysfunction of cerebral microvasculature induced by type 1 diabetes (T1D) are not fully understood. We hypothesized that in cerebral microvascular endothelium, α-processing of amyloid precursor protein (APP) is impaired by T1D. In cerebral microvessels derived from streptozotocin (STZ)-induced T1D mice protein levels of APP and its α-processing enzyme, a disintegrin and metalloprotease 10 (ADAM10) were significantly decreased, along with down-regulation of adenylate cyclase 3 (AC3) and enhanced production of thromboxane A2 (TXA2). In vitro studies in human brain microvascular endothelial cells (BMECs) revealed that knockdown of AC3 significantly suppressed ADAM10 protein levels, and that activation of TXA2 receptor decreased APP expression. Furthermore, levels of soluble APPα (sAPPα, a product of α-processing of APP) were significantly reduced in hippocampus of T1D mice. In contrast, amyloidogenic processing of APP was not affected by T1D in both cerebral microvessels and hippocampus. Most notably, studies in endothelial specific APP knockout mice established that genetic inactivation of APP in endothelium was sufficient to significantly reduce sAPPα levels in the hippocampus. In aggregate, our findings suggest that T1D impairs non-amyloidogenic processing of APP in cerebral microvessels. This may exert detrimental effect on local concentration of neuroprotective molecule, sAPPα, in the hippocampus.

The platelet phenotype in patients with ST-segment elevation myocardial infarction is different from non–ST-segment elevation myocardial infarction

It is assumed that platelets in diseased conditions share similar properties to platelets in healthy conditions, although this has never been examined in detail for myocardial infarction (MI). We examined platelets from patients with ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI) compared with platelets from healthy volunteers to evaluate for differences in platelet phenotype and function. Platelet activation was examined and postreceptor signal transduction pathways were assessed. Platelet-derived plasma biomarkers were evaluated by receiver operator characteristic curve analysis. Maximum platelet activation through the thromboxane receptor was greater in STEMI than in NSTEMI but less through protease-activated receptor 1. Extracellular-signal related-kinase 5 activation, which can activate platelets, was increased in platelets from subjects with STEMI and especially in platelets from patients with NSTEMI. Matrix metalloproteinase 9 (MMP9) protein content and enzymatic activity were several-fold greater in platelets with MI than in control. Mean plasma MMP9 concentration in patients with MI distinguished between STEMI and NSTEMI (area under curve [AUC] 75% [confidence interval (CI) 60-91], P = 0.006) which was superior to troponin T (AUC 66% [CI 48-85, P = 0.08), predicting STEMI with 80% sensitivity (95% CI 56-94), 90% specificity (CI 68-99), 70% AUC (CI 54-86, P < 0.0001), and NSTEMI with 50% sensitivity (CI 27-70), 90% specificity (CI 68-99), 70% AUC (CI 54-86, P = 0.03). Platelets from patients with STEMI and NSTEMI show differences in platelet surface receptor activation and postreceptor signal transduction, suggesting the healthy platelet phenotype in which antiplatelet agents are often evaluated in preclinical studies is different from platelets in patients with MI.

Lipopolysaccharide potentiates platelet responses via toll-like receptor 4-stimulated Akt-Erk-PLA2 signalling.

Lipopolysaccharide (LPS) from the cell envelope of Gram-negative bacteria is a principal cause of the symptoms of sepsis. LPS has been reported to modulate the function of platelets although the underlying mechanisms of LPS action in these cells remain unclear. Platelets express the Toll-like receptor 4 (TLR4) which serves as a receptor for LPS, although the potential role of TLR4 and associated cell signalling in controlling platelet responses to LPS has not been extensively explored. In this study, we therefore investigated the actions of LPS prepared from different strains of Escherichia coli on platelet function, the underlying signalling mechanisms, and the potential role of TLR4 in orchestrating these. We report that LPS increased the aggregation of washed platelets stimulated by thromboxane (U46619) or GPVI collagen receptor agonists, effects that were prevented by a TLR4 antagonist. Associated with this, LPS enhanced fibrinogen binding, P-selectin exposure and reactive oxygen species (ROS) release. Increase of ROS was found to be important for the actions of LPS on platelets, since these were inhibited in the presence of superoxide dismutase or catalase. The effects of LPS were associated with phosphorylation of Akt, ERK1/2 and PLA2 in stimulated platelets, and inhibitors of PI3-kinase, Akt and ERK1/2 reduced significantly LPS enhanced platelet function and associated ROS production. Furthermore, inhibition of platelet cyclooxygenase or the thromboxane receptor, revealed an important role for thromboxane A2. We therefore conclude that LPS increases human platelet activation through a TLR4-PI3K-Akt-ERK1/2-PLA2 -dependent pathway that is dependent on ROS and TXA2 formation.

F2-isoprostanes can mediate bleomycin-induced lung fibrosis.

F2-isoprostanes (F2-IsoPs) have been considered markers of oxidative stress in various pulmonary diseases, but little is known about their possible role in pulmonary fibrosis. In this study, we have investigated the potential key role of F2-IsoPs as markers and mediators of bleomycin (BLM)-induced pulmonary fibrosis in rats. During the in vivo study, plasma F2-IsoPs showed a peak at 7 days and remained elevated for the entire experimental period. Lung F2-IsoP content nearly tripled 7 days following the intratracheal instillation of BLM, and by 28 days, the value increased about fivefold compared to the controls. Collagen deposition correlated with F2-IsoP content in the lung. Furthermore, from day 21 onwards, lung sections from BLM-treated animals showed α-smooth muscle actin (α-SMA) positive cells, which were mostly evident at 28 days. In vitro studies performed in rat lung fibroblasts (RLF) demonstrated that either BLM or F2-IsoPs stimulated both cell proliferation and collagen synthesis. Moreover, RLF treated with F2-IsoPs showed a significant increase of α-SMA expression compared to control, indicating that F2-IsoPs can readily activate fibroblasts to myofibroblasts. Our data demonstrated that F2-IsoPs can be mediators of key events for the onset and development of lung fibrosis, such as cell proliferation, collagen synthesis and fibroblast activation. Immunocytochemistry analysis, inhibition and binding studies demonstrated the presence of the thromboxane A2 receptor (TP receptor) on lung fibroblasts and suggested that the observed effects may be elicited through the binding to this receptor. Our data added a new perspective on the role of F2-IsoPs in lung fibrosis by providing evidence of a profibrotic role for these mediators in the pathogenesis of pulmonary fibrosis.

Biological substantiation of antipsychotic-associated pneumonia: Systematic literature review and computational analyses.

IntroductionAntipsychotic (AP) safety has been widely investigated. However, mechanisms underlying AP-associated pneumonia are not well-defined.AimThe aim of this study was to investigate the known mechanisms of AP-associated pneumonia through a systematic literature review, confirm these mechanisms using an independent data source on drug targets and attempt to identify novel AP drug targets potentially linked to pneumonia.MethodsA search was conducted in Medline and Web of Science to identify studies exploring the association between pneumonia and antipsychotic use, from which information on hypothesized mechanism of action was extracted. All studies had to be in English and had to concern AP use as an intervention in persons of any age and for any indication, provided that the outcome was pneumonia. Information on the study design, population, exposure, outcome, risk estimate and mechanism of action was tabulated. Public repositories of pharmacology and drug safety data were used to identify the receptor binding profile and AP safety events. Cytoscape was then used to map biological pathways that could link AP targets and off-targets to pneumonia.ResultsThe literature search yielded 200 articles; 41 were included in the review. Thirty studies reported a hypothesized mechanism of action, most commonly activation/inhibition of cholinergic, histaminergic and dopaminergic receptors. In vitro pharmacology data confirmed receptor affinities identified in the literature review. Two targets, thromboxane A2 receptor (TBXA2R) and platelet activating factor receptor (PTAFR) were found to be novel AP target receptors potentially associated with pneumonia. Biological pathways constructed using Cytoscape identified plausible biological links potentially leading to pneumonia downstream of TBXA2R and PTAFR.ConclusionInnovative approaches for biological substantiation of drug-adverse event associations may strengthen evidence on drug safety profiles and help to tailor pharmacological therapies to patient risk factors.

Nonsteroidal Anti-Inflammatory Drugs: Exploiting Bivalent COXIB/ TP Antagonists for the Control of Cardiovascular Risk.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are some of the most widely prescribed or dispensed over the counter analgesics and antipyretics that act by inhibiting prostaglandins and thromboxane synthesis. After the identification of a second isoform of COX, the pharmaceutical research focused on developing COX-2- selective drugs (COXIBs) considered as second generation NSAIDs that would retain the anti-inflammatory and analgesic activities of traditional NSAID without blunting the gastrointestinal cytoprotection sustained by COX1-derived products such as PGE2. However, while several clinical trials confirmed a gastrointestinal safer profile of COXIBs vs unselective COX inhibitors, increasing evidence for potential cardiovascular risk associated with COXIBs rapidly emerged. Today, there are no really safe NSAIDs to be used in chronic pain and anti-inflammatory treatments, as an adequate therapy associated with a minimal gastrointestinal damage and cardiovascular toxicity is yet to be developed. Here, we present evidences that combining the anti-aggregating and antiatherotrombotic activities of a thromboxane receptor antagonist with the antiinflammatory activity of a COXIB we could obtain a new multitarget drug providing protection against the harmful activities mediated by the COXIB component, yet exploiting its recognized therapeutic advantages as a gastrointestinal-safer anti-inflammatory drug. We also summarize recent progress achieved in this field of research and possible new strategies to obtain a new bivalent compound. This possible third-generation NSAID with a safer pharmacological profile, will have all the pharmacological characteristics for the long-term therapy of chronic disorders such as inflammatory diseases or selected forms of cancer.

Involvement of thromboxane A2 in interleukin-31-induced itch-associated response in mice.

Atopic dermatitis is a chronic and severe pruritic skin disease. Interlukin-31 (IL-31) has been recently demonstrated to be one of the key pruritogens in atopic dermatitis. However, the mechanisms underlying IL-31-induced itching remains unclear. In our previous study, we have shown that thromboxane (TX) A2 is involved in itch-associated responses in mice with atopy-like skin diseases. IL-31 was given intradermally into the rostral back of ICR mice and the hind-paw scratching to the injection site were counted. Expression of TX synthase and IL-31 receptors were analyzed using immunohistochemical staining or RT-PCR in mouse skin or primary cultures of mouse keratinocytes. The concentration of TXB2, a metabolite of TXA2, in the skin and the culture medium of primary cultures of mouse keratinocytes was measured using enzyme immunoassay. The concentration of intracellular Ca2+ ions in mouse keratinocytes was measured using the calcium imaging method. An intradermal injection of IL-31 elicited scratching, an itch-related response, in mice. The scratching was inhibited by TP TXA2 receptor antagonist DCHCH. The distribution of TX synthase and IL-31RA receptor was mainly epidermal keratinocytes in the skin. The primary cultures of keratinocytes expressed the mRNAs of TX synthase and IL-31 receptors. IL-31 increased the concentration of TXB2, which was inhibited by TX synthase inhibitor sodium ozagrel and EGTA, in the skin and the culture medium of primary cultures of keratinocytes. IL-31 increased the concentration of intracellular Ca2+ ions in mouse keratinocytes. It is suggested that IL-31 elicits itch-associated responses through TXA2 produced from keratinocytes.

Sex differences in the role of phospholipase A2 -dependent arachidonic acid pathway in the perivascular adipose tissue function in pigs.

The fat surrounding blood vessels (perivascular adipose tissue or PVAT) releases vasoactive compounds that regulate vascular smooth muscle tone. There are sex differences in the regulation of vascular tone, but, to date, no study has investigated whether there are sex differences in the regulation of blood vessel tone by PVAT. This study has identified that the cyclooxygenase products thromboxane and PGF2α are released from coronary artery PVAT from pigs. Thromboxane appears to mediate the PVAT-induced contraction in arteries from females, whereas PGF2α appears to mediate the contraction in arteries from males. These sex differences in the role of these prostanoids in the PVAT-induced contraction can be explained by a greater release of thromboxane from PVAT from female animals and greater sensitivity to PGF2α in the porcine coronary artery from males. Previous studies have demonstrated that perivascular adipose tissue (PVAT) causes vasoconstriction. In this present study, we determined the role of cyclooxygenase-derived prostanoids in this contractile response and determined whether there were any sex differences in the regulation of vascular tone by PVAT. Contractions in isolated segments of coronary arteries were determined using isolated tissue baths and isometric tension recording. Segments were initially cleaned of PVAT, which was then re-added to the tissue bath and changes in tone measured over 1h. Levels of PGF2α and thromboxane B2 (TXB2 ) were quantified by ELISA, and PGF2α (FP) and thromboxane A2 (TP) receptor expression determined by Western blotting. In arteries from both male and female pigs, re-addition of PVAT caused a contraction, which was partially inhibited by the cyclooxygenase inhibitors indomethacin and flurbiprofen. The FP receptor antagonist AL8810 attenuated the PVAT-induced contraction in arteries from males, whereas the TP receptor antagonist GR32191B inhibited the PVAT-induced contraction in arteries from females. Although there was no difference in PGF2α levels in PVAT between females and males, PGF2α produced a larger contraction in arteries from males, correlating with a higher FP receptor expression. In contrast, release of TXB2 from PVAT from females was greater than from males, but there was no difference in the contraction by the TXA2 agonist U46619, or TP receptor expression in arteries from different sexes. These findings demonstrate clear sex differences in PVAT function in which PGF2α and TXA2 antagonists can inhibit the PVAT-induced vasoconstriction in male and female PCAs, respectively.

Antagonist of thromboxane A2 receptor by SQ29548 lowers DOCA-induced hypertension in diabetic rats

Diabetes is one of high risk factors for cardiovascular diseases, including atherosclerosis and hypertension. This study was conducted to elucidate whether and how thromboxane receptor (TPr) activation contributes to hypertension in diabetes. Human umbilical vein endothelial cells (HUVECs) were cultured. The phosphorylated levels of endothelial nitric oxide synthase (eNOS) and Akt were monitored by western blot. Endothelial function was determined by organ bath. High glucose (HG) or thromboxane A2 mimetic U46619 significantly reduced the levels of p-eNOS and p-Akt in cultured HUVECs, which were reversed by inhibition of TPr. HG/U46619-induced reductions of p-eNOS and p-Akt were accompanied with increases of total and phosphorylated tumor suppressor phosphatase and tensin homolog on chromosome 10 (PTEN). PTEN siRNA restored Akt-eNOS signaling in cells treated with HG. In rats, streptozotocin-induced hyperglycemia was associated with aortic PTEN upregulation and reductions of p-Akt and p-eNOS. TPr antagonist SQ29548 ablated these alterations and reduced blood pressure in rats with DOCA-induced hypertensive. In conclusion, hyperglycemia activates thromboxane A2 receptor to augment DOCA-induced high blood pressure in rats via the PTEN-Akt-eNOS signaling.

Pathway and network-based analysis of genome-wide association studies and RT-PCR validation in polycystic ovary syndrome.

The purpose of this study was to identify promising candidate genes and pathways in polycystic ovary syndrome (PCOS). Microarray dataset GSE345269 obtained from the Gene Expression Omnibus database includes 7 granulosa cell samples from PCOS patients, and 3 normal granulosa cell samples. Differentially expressed genes (DEGs) were screened between PCOS and normal samples. Pathway enrichment analysis was conducted for DEGs using ClueGO and CluePedia plugin of Cytoscape. A Reactome functional interaction (FI) network of the DEGs was built using ReactomeFIViz, and then network modules were extracted, followed by pathway enrichment analysis for the modules. Expression of DEGs in granulosa cell samples was measured using quantitative RT-PCR. A total of 674 DEGs were retained, which were significantly enriched with inflammation and immune-related pathways. Eight modules were extracted from the Reactome FI network. Pathway enrichment analysis revealed significant pathways of each module: module 0, Regulation of RhoA activity and Signaling by Rho GTPases pathways shared ARHGAP4 and ARHGAP9; module 2, GlycoProtein VI-mediated activation cascade pathway was enriched with RHOG; module 3, Thromboxane A2 receptor signaling, Chemokine signaling pathway, CXCR4-mediated signaling events pathways were enriched with LYN, the hub gene of module 3. Results of RT-PCR confirmed the finding of the bioinformatic analysis that ARHGAP4, ARHGAP9, RHOG and LYN were significantly upregulated in PCOS. RhoA-related pathways, GlycoProtein VI-mediated activation cascade pathway, ARHGAP4, ARHGAP9, RHOG and LYN may be involved in the pathogenesis of PCOS.

P2Y12 antibody inhibits platelet activity and protects against thrombogenesis

Given that platelet hyperactivity is known to give rise to thrombotic disorders, new and/or novel antiplatelet therapies are constantly being developed to add to, or to complement the current arsenal of agents. To this end, adenosine diphosphate (ADP) is an important platelet activator that acts by binding to the G-protein coupled P2Y1 and P2Y12 receptors. Although the contribution of the P2Y12 receptor to the genesis of thrombosis is well established, the parenteral arsenal of drugs targeting this receptor in clinical use is limited to cangrelor. In this study, we investigated the potential antiplatelet activity of an antibody targeting the ligand-binding domain of the P2Y12 receptor (abbreviated P2Y12Ab). Our in vitro studies revealed that the P2Y12Ab could effectively inhibit aggregation induced by ADP, as well as that triggered by the thromboxane receptor agonist U46619. Additionally, using FACS analysis, we observed reduced P-selectin, phosphatidylserine exposure and integrin activation in the presence of P2Y12Ab. As for its in vivo effects, the P2Y12Ab also demonstrated protection against thrombus formation; albeit this was accompanied with a bleeding diathesis (longer bleeding time). Notably, this inhibitory profile is consistent with that observed with oral anti-P2Y12 agents. Collectively, our findings demonstrate that the P2Y12Ab functionally blocks platelet activity in vitro and in vivo, and support the notion that it can be purposed as a parenteral antiplatelet agent, to be used in conjunction with and/or as a complement to current antiplatelet therapies.

Vasodilatory effects of mulberry (Morus spp.) leaf extract on porcine cerebral arteries in vitro: Possible underlying mechanisms

Vasodilatory effects of mulberry leaf extract (MLE) and its possible underlying mechanisms on porcine basilar artery (PBA) were investigated by measuring changes in isometric tension in vitro. MLE slightly relaxed 60mMKCl pre-contracted PBA rings (9.4% at 540μg/mL). A treatment with MLE induced extensive relaxation under pre-contraction with 0.1μM U-46619 (EC50=49.4μg/mL). Neither endothelial denudation nor treatment with atenolol (10μM) affected MLE-induced relaxation. Relaxation induced by MLE (540μg/mL) was significantly attenuated by cimetidine (10μM). MLE inhibited angiotensin I-induced contraction in endothelium-intact PBA rings (EC50=25μg/mL), similar to captopril. Therefore, the possible mechanisms underlying MLE-induced relaxation in PBA might be mediated through: (1) functional antagonism of thromboxane A2 receptors; (2) suppression of angiotensin I-induced contraction; (3) Ca2+ influx inhibition; (4) stimulation of H2-receptors. Moreover, MLE contained significant amounts of nitrite, nitrate and several phenolic compounds, possibly associated with MLE-induced relaxation.

Regulated expression of the TPβ isoform of the human T prostanoid receptor by the tumour suppressors FOXP1 and NKX3.1: Implications for the role of thromboxane in prostate cancer

The prostanoid thromboxane (TX)A2 signals through the TPα and TPβ isoforms of T Prostanoid receptor (TP) that are transcriptionally regulated by distinct promoters termed Prm1 and Prm3, respectively, within the TBXA2R gene. We recently demonstrated that expression of TPα and TPβ is increased in PCa, differentially correlating with Gleason grade and with altered CpG methylation of the individual Prm1/Prm3 regions within the TBXA2R. The current study sought to localise the sites of CpG methylation within Prm1 and Prm3, and to identify the main transcription factors regulating TPβ expression through Prm3 in the prostate adenocarcinoma PC-3 and LNCaP cell lines.Bisulfite sequencing revealed extensive differences in the pattern and status of CpG methylation of the individual Prm1 and Prm3 regions that regulate TPα and TPβ expression, respectively, within the TBXA2R. More specifically, Prm1 is predominantly hypomethylated while Prm3 is hypermethylated across its entire sequence in PC-3 and LNCaP cells. Furthermore, the tumour suppressors FOXP1 and NKX3.1, strongly implicated in PCa development, were identified as key transcription factors regulating TPβ expression through Prm3 in both PCa cell lines. Specific siRNA-disruption of FOXP1 and NKX3.1 each coincided with up-regulated TPβ protein and mRNA expression, while genetic-reporter and chromatin immunoprecipitation (ChIP) analyses confirmed that both FOXP1 and NKX3.1 bind to cis‑elements within Prm3 to transcriptionally repress TPβ in the PCa lines. Collectively these data identify Prm3/TPβ as a bona fide target of FOXP1 and NKX3.1 regulation, providing a mechanistic basis, at least in part, for the highly significant upregulation of TPβ expression in PCa.

The isoflavonoid tectorigenin has better antiplatelet potential than acetylsalicylic acid

BackgroundOne reason for the lower incidence of cardiovascular diseases in Asian countries may be the high intake of isoflavonoids and their antiplatelet effects may be an important factor. To date, there is limited comparison of a range of isoflavonoids and knowledge of their effects at different levels of platelet aggregation. PurposeTo screen the antiplatelet effects of a number of isoflavonoids on the arachidonic acid based aggregation pathway and investigate how the antiplatelet activity might occur. MethodsThe antiplatelet effects were first screened in whole human blood where platelet aggregation was induced by arachidonic acid. Further analysis was targeted at search of the mechanism of action. ResultsThirteen of the eighteen tested isoflavonoids had significant inhibitory effect on platelet aggregation in whole human blood. Genistein had the same potency as clinically used acetylsalicylic acid (ASA) while tectorigenin was clearly stronger than ASA. Further analyses showed that the effect of tectorigenin was not based on inhibition of cyclooxygenase-1 in contrast to ASA or thromboxane synthase but by competitive antagonism at thromboxane receptors. ConclusionTectorigenin is a more potent antiplatelet compound than ASA and thus an interesting substance for further testing.

Aluminum exposure at human dietary levels promotes vascular dysfunction and increases blood pressure in rats: A concerted action of NAD(P)H oxidase and COX-2.

Aluminum (Al) is a non-essential metal and a significant environmental contaminant and is associated with a number of human diseases including cardiovascular disease. We investigated the effects of Al exposure at doses similar to human dietary levels on the cardiovascular system over a 60day period. Wistar male rats were divided into two major groups and received orally: 1) Low aluminum level - rats were subdivided and treated for 60days as follows: a) Untreated - ultrapure water; b) AlCl3 at a dose of 8.3mg/kg bw for 60days, representing human Al exposure by diet; and 2) High aluminum level - rats were subdivided and treated for 42days as follows: C) Untreated - ultrapure water; d) AlCl3 at 100mg/kg bw for 42days, representing a high level of human exposure to Al. Effects on systolic blood pressure (SBP) and vascular function of aortic and mesenteric resistance arteries (MRA) were studied. Endothelium and smooth muscle integrity were evaluated by concentration-response curves to acetylcholine (ACh) and sodium nitroprusside. Vasoconstrictor responses to phenylephrine (Phe) in the presence and absence of endothelium and in the presence of the NOS inhibitor L-NAME, the potassium channels blocker TEA, the NAD(P)H oxidase inhibitor apocynin, superoxide dismutase (SOD), the non-selective COX inhibitor indomethacin and the selective COX-2 inhibitor NS 398 were analyzed. Vascular reactive oxygen species (ROS), lipid peroxidation and total antioxidant capacity, were measured. The mRNA expressions of eNOS, NAD(P)H oxidase 1 and 2, SOD1, COX-2 and thromboxane A2 receptor (TXA-2 R) were also investigated. Al exposure at human dietary levels impaired the cardiovascular system and these effects were almost the same as Al exposure at much higher levels. Al increased SBP, decreased ACh-induced relaxation, increased response to Phe, decreased endothelial modulation of vasoconstrictor responses, the bioavailability of nitric oxide (NO), the involvement of potassium channels on vascular responses, as well as increased ROS production from NAD(P)H oxidase and contractile prostanoids mainly from COX-2 in both aorta and mesenteric arteries. Al exposure increased vascular ROS production and lipid peroxidation as well as altered the antioxidant status in aorta and MRA. Al decreased vascular eNOS and SOD1 mRNA levels and increased the NAD(P)H oxidase 1, COX-2 and TXA-2 R mRNA levels. Our results point to an excess of ROS mainly from NAD(P)H oxidase after Al exposure and the increased vascular prostanoids from COX-2 acting in concert to decrease NO bioavailability, thus inducing vascular dysfunction and increasing blood pressure. Therefore, 60-day chronic exposure to Al, which reflects common human dietary Al intake, appears to pose a risk for the cardiovascular system.

Role of ADP ribosylation factor6− Cytohesin1−PhospholipaseD signaling axis in U46619 induced activation of NADPH oxidase in pulmonary artery smooth muscle cell membrane

Treatment of human pulmonary artery smooth muscle cells (HPASMCs) with the thromboxane A2 receptor antagonist, SQ29548 inhibited U46619 stimulation of phospholipase D (PLD) and NADPH oxidase activities in the cell membrane. Pretreatment with apocynin inhibited U46619 induced increase in NADPH oxidase activity. The cell membrane contains predominantly PLD2 along with PLD1 isoforms of PLD. Pretreatment with pharmacological and genetic inhibitors of PLD2, but not PLD1, attenuated U46619 stimulation of NADPH oxidase activity. U46619 stimulation of PLD and NADPH oxidase activities were insensitive to BFA and Clostridium botulinum C3 toxin; however, pretreatment with secinH3 inhibited U46619 induced increase in PLD and NADPH oxidase activities suggesting a major role of cytohesin in U46619-induced increase in PLD and NADPH oxidase activities. Arf-1, Arf-6, cytohesin-1 and cytohesin-2 were observed in the cytosolic fraction, but only Arf-6 and cytohesin-1 were translocated to the cell membrane upon treatment with U46619. Coimmunoprecipitation study showed association of Arf-6 with cytohesin-1 in the cell membrane fraction. In vitro binding of GTPγS with Arf-6 required the presence of cytohesin-1 and that occurs in BFA insensitive manner. Overall, BFA insensitive Arf6−cytohesin1 signaling axis plays a pivotal role in U46619-mediated activation of PLD leading to stimulation of NADPH oxidase activity in HPASMCs.

Differential TBXA2 receptor transcript stability is dependent on the C924T polymorphism

BackgroundIn order to better characterize the molecular mechanisms involved in processing mutated transcripts, we investigated the post-transcriptional role of the C924T polymorphism (rs4523) located in the 3′ region of the TBXA2R gene. Methods and ResultsExperiments of dose response with Actinomycin D on MEG-01 human cell line showed a significant decrease on cell viability that was more evident on cells treated for 24h. In addition, we showed that treatments with 5–10μM, 15μM and 20μM of actinomycin D reduced cell viability by 44%, 72% and 75%, respectively, compared to the control group. Conversely, the samples treated with 1μM of actinomycin D did not show significant difference on cell viability as compared to the control group. Analysis of the steady state mRNA level of TBXA2R by qRT-PCR evidenced an increase in mRNA stability for the wild type (C) compared to the mutant (T) allele. Furthermore, the expression levels of TBXA2R on wild type (CC) and mutant type (TT) patients, based on C924T polymorphism, were analyzed. The wild type showed a higher expression of TBXA2 receptor also with two different degrees of glycosylation (55 and 64kDa), when compared to the mutant. These observations correlated with platelet aggregation, which was reduced in TT, independently of the platelet aggregation stimuli. ConclusionsThe instability of the TBXA2R transcript and the lack of effect on platelet aggregation might suggest a protective role for the TBXA2R TT genotype against atherothrombosis and its complications in high-risk aspirin-treated patients.