Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.5.1.19 (NOS)
 7,285 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Implantation is characterized by an inflammatory-like response with expansion of extracellular fluid volume, increased vascular permeability, and vasodilatation. These effects are believed to be mediated at the paracrine level by prostaglandin E2 and platelet-activating factor (PAF), but the cellular mechanism (or mechanisms) remains largely unknown. We demonstrate that PAF receptor (PAF-R) immunoreactivity and mRNA are detected in proliferative and secretory endometrial glands, however, the responsiveness of endometrium to physiological concentrations of PAF is confined predominantly to the secretory endometrium. Semiquantitative reverse transcription-polymerase chain reaction revealed that PAF-R transcript levels were highest in the mid-late proliferative and late secretory phases of the cycle. Interaction of PAF with its receptor resulted in the rapid release of nitric oxide (NO), increased expression of vascular endothelial growth factor (VEGF), and activation of FAKpp125, a focal adhesion kinase, demonstrating that the PAF-R is functionally active. Inhibition of NO synthesis by NG-monomethyl-L-arginine produced dose-dependent attenuation of PAF-evoked NO release, indicating NOS activation; the dependency of PAF-evoked NO release on PKC and extracellular Ca2+ was confirmed by PKC inhibitor Ro 31-8220 and by the removal of extracellular Ca2+. PAF up-regulated VEGF gene expression in a concentration- and time-dependent fashion in human endometrial epithelial cell lysates. Transcription of VEGF was rapidly followed by secretion of the protein. These data support our premise that this autocoid acts as an angiogenic mediator in the regeneration of the endometrium after menses and as a vasodilator to promote blastocyst attachment during the implantation process.
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PMID:Localization, quantification, and activation of platelet-activating factor receptor in human endometrium during the menstrual cycle: PAF stimulates NO, VEGF, and FAKpp125. 965 23

Ovulation, recurring every reproductive cycle of the mammalian female and triggered by a surge of luteinizing hormone (LH) released from the pituitary is an essential prerequisite for fertilization and subsequent embryonic development. Here we shall review two of the biological responses leading to follicle rupture -- vascular changes and proteolysis. Naturally, our present knowledge is based mainly on work in a few species, such as the rat, the mouse and, to lesser extent the pig and monkeys and observations in the human. Therefore any generalizations to other mammals, should be considered as a working hypothesis yet to be confirmed. The LH surge stimulates, in the preovulatory follicles, a cascade of proteolytic enzymes, including plasminogen activator (PA), plasmin and matrix metalloproteinases (MMPs). These enzymes bring about the degradation of perifollicular matrix and, most notably, the decomposition of the meshwork of collagen fibers which provides the strength to follicular wall. Pharmacological blockage of any of these enzymes resulted in the reduction of ovulation rate. The increased ovarian proteolytic activity associated with ovulation is controlled by locally produced specific inhibitors, plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metalloproteases-1 (TIMP-1). The increased synthesis of these two specific proteinase inhibitors in the theca of growing follicles ensures their development by protecting them from enzymes diffusing from ovulatory follicles. The stimulation of ovulation by the gonadotropin results in an increase in follicular blood flow, hyperemia, increase in vascular permeability and a marked increase in follicular volume. These vascular changes and the proteolytic activity are triggered either directly by LH or by local mediators and factors produced in response to the gonadotropic stimulus. These mediators allow the tight coordination of these two cascades culminating in the rupture of follicle wall. We shall review here, briefly, the various mediatory systems that have been implicated in follicle rupture. These include steroids, vascular endothelial growth factor (VEGF), cytokines, eicosanoids, platelet activating factor (PAF), nitric oxide and nitric oxide synthase (NO/NOS), kinins and oxygen radicals.
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PMID:Molecular aspects of mammalian ovulation. 1007 49

Gene therapy is based on the delivery of exogenous genetic material in order to influence the endogenous genetic components involved in disease development. This new therapeutic approach has been suggested to have great potential in the treatment of insufficient angiogenesis or in prevention of restenosis after balloon angioplasty of atherosclerotic arteries. As both vascular endothelial growth factor (VEGF) and nitric oxide (NO) exert beneficial effects on vascular physiology, we studied the generation of both compounds after in vitro transfection of relevant genes. The plasmid vectors, containing VEGF cDNA were constructed and lipotransfected into vascular smooth muscle cells (VSMC). Transfected cells generated up to a few nanograms of VEGF, which induced proliferation of endothelial cells. VSMC transfected with another plasmid, containing endothelial constitutive NO synthase (ecNOS) cDNA generated micromolar quantities of nitrite. Moreover, such NO-producing cells synthesized significantly more VEGF than VSMC transfected with control plasmids. Thus, the study demonstrated that transfer of VEGF and/or NOS genes to VSMC led to the production of measurable amounts of both VEGF protein and NO. Additionally, we evidenced that NO can enhance the endogenous generation of VEGF. A new protective mechanism of NO has been thus revealed.
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PMID:Gene transfer of vascular endothelial growth factor and endothelial nitric oxide synthase--implications for gene therapy in cardiovascular diseases. 1060 37

VEGF-A induces angiogenesis and regulates endothelial function via production and release of nitric oxide (NO), which is produced by endothelial nitric oxide synthase (eNOS). While the upregulation of eNOS expression has been shown to be mediated via VEGF receptor KDR, there is controversy about which of the VEGF receptors triggers the release of nitric oxide in endothelial cells. In order to determine the levels of NO produced in response to VEGF-A stimulation in different endothelial cells, a reporter assay measuring the formation of cGMP as the direct product of NO-induced activation of guanylate cyclase was performed. Using two independent experimental strategies, we were able to prove that VEGF receptor KDR, but not VEGF receptor Flt-1, can induce NO release in endothelial cells. First, we made use of porcine aortic endothelial cells (PAE) expressing either KDR or Flt-1. While KDR-expressing PAE/KDR cells responded to VEGF-A stimulation with a significant elevation of intracellular cGMP already after 2 min, Flt-1-expressing PAE/Flt-1 cells did not show any signal in this RIA-based cGMP assay. In a second experimental strategy freshly isolated human umbilical vein endothelial cells (HUVEC) were stimulated either with the KDR-specific ligand VEGF-E or with the Flt-1-specific ligand PIGF-2. VEGF-E induces cGMP elevation in this setting, while PIGF-2 was unable to do so, clearly demonstrating that KDR is responsible for NO release in endothelial cells. In our assays cGMP formation is fully dependent on NO generation since the NOS inhibitor L-NAME can block this VEGF-A-induced action. These data show that the VEGF receptor KDR is responsible for NO release in endothelial cells, highlighting a new function of KDR and further supporting the importance of KDR in the regulation of the vasculature.
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PMID:A novel function of VEGF receptor-2 (KDR): rapid release of nitric oxide in response to VEGF-A stimulation in endothelial cells. 1060 Apr 73

The angiogenic proteins basic fibroblast growth factor (bFGF; FGF-2) and vascular endothelial growth factor 121 (VEGF(121)) are each able to enhance the collateral-dependent blood flow after bilateral femoral artery ligation in rats. To study the effect of nitric oxide (NO) synthase (NOS) inhibition on bFGF- or VEGF(121)-induced blood flow expansion, the femoral arteries of male Sprague-Dawley rats were ligated bilaterally, and the animals were given tap water [non-N(G)-nitro-L-arginine methyl ester (L-NAME) group; n = 36] or water that contained L-NAME (L-NAME group; 2 mg/ml, n = 36). Animals from each group were further divided into three subgroups: vehicle (n = 12), bFGF (5 microg x kg(-1) x day(-1), n = 12), or VEGF(121) (10 microg x kg(-1) x day(-1), n = 12). Growth factors were delivered via intra-arterial infusion with osmotic pumps over days 1-14. On day 16, after a 2-day delay to permit clearance of bFGF and VEGF from the circulation, maximal collateral blood flow was determined by (85)Sr- and (141)Ce-labeled microspheres during treadmill running. L-NAME (approximately 137 mg x kg(-1) x day(-1)) for 18 days increased systemic blood pressure (approximately 26%, P<0.001). In the absence of L-NAME, collateral-dependent blood flows to the calf muscles were greater in the VEGF(121)- and bFGF-treated subgroups (85 +/- 4.5 and 80 +/- 2.9 ml x min(-1) x 100 g(-1), respectively) than in the vehicle subgroup (49 +/- 3.0 ml x min(-1) x 100 g(-1), P<0.001). In the presence of NOS inhibition by L-NAME, blood flows to the calf muscles were essentially equivalent among the three subgroups (54 +/- 3.0, 56 +/- 5.1, and 47 +/- 2.0 ml x min(-1) x 100 g(-1) in the bFGF-, VEGF(121)-, and vehicle-treated subgroups, respectively) and were not different from the blood flow in the non-L-NAME vehicle subgroup. Our results therefore indicate that normal NO production is essential for the enhanced vascular remodeling induced by exogenous bFGF or VEGF(121) in this rat model of experimental peripheral arterial insufficiency. These results imply that a blunted endothelial NO production could temper vascular remodeling in response to these angiogenic growth factors.
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PMID:VEGF(121)- and bFGF-induced increase in collateral blood flow requires normal nitric oxide production. 1117 52

Our previous study showed that genetic disruption of nitric oxide (NO) synthase II (NOS II) expression inhibits the metastatic ability of non-immunogenic B16 melanoma cells in syngeneic mice. In the present study, the mechanisms for this metastasis suppression were determined. B16-BL6 and B16-F10 murine melanoma cells were injected i.v. into syngeneic wild-type (NOS II(+/+)) and NOS II-null (NOS II(-/-)) C57BL/6 mice. Both melanoma cells produced less and smaller experimental pulmonary metastases in NOS II(-/-) mice than in NOS II(+/+) mice. Moreover, less metastatic pleural effusion was observed in NOS II(-/-) mice than in NOS II(+/+) mice. Immunohistochemical analyses indicated that absence of NOS II expression was correlated with decreased vascular endothelial growth factor expression and tumor-associated vascular formation. After activation with lipopolysaccharide and IFN-gamma, neither melanoma cell line produced detectable levels of NO. Our data demonstrate that tumor-induced expression of host NOS II enhances melanoma metastasis and pleural effusion, at least in part, through regulation of vascular formation and vascular permeability.
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PMID:Genetic disruption of host nitric oxide synthase II gene impairs melanoma-induced angiogenesis and suppresses pleural effusion. 1126 68

The expression of a primary initiator of tumor angiogenic responses, vascular endothelial growth factor (VEGF), may be induced by nitric oxide (NO) in carcinoma cells. However, the net impact of NO on carcinogenesis remains unclear, because manipulation of NO levels has been shown to either stimulate or inhibit tumor growth. We have investigated the relationship between inducible NO synthase (NOS II), VEGF expression, and growth of B16-F1 melanoma over 14 days in wild-type (NOS II+/+) mice and in those in which the gene for NOS II has been deleted (NOS II-/-). B16-F1 tumor growth was measured as wet weight of the excised tissue. Tumor NOS II and VEGF localization were evaluated by immunohistochemistry, and VEGF mRNA levels were measured by Northern blot analysis. In NOS II+/+ mice inoculated with B16-F1 melanoma cells, macroscopic tumors were always observed at 14 days; however, 22% of NOS II-/- mice had no detectable tumor mass. Immunoreactive NOS II was detected in tumor cells of tumors grown in NOS II+/+ but not in NOS II-/- mice. Although immunoreactive VEGF was detected in the granules of tumor-associated mast cells from both NOS II+/+ and NOS II-/- mice, VEGF mRNA expression in tumors from NOS II-/- was half that in NOS II+/+ mice. Neither NOS II inhibition, exogenous NO, nor peroxynitrite influenced DNA synthesis in culture B16-F1 melanoma cells. The NO donor did not alter either VEGF mRNA levels or degranulation in cultures of the mast cell line RBL-2H3, but peroxynitrite increased both VEGF mRNA expression and degranulation. We conclude that host expression of NOS II contributes to induction of NOS II in the tumor and to melanoma growth in vivo, possibly by regulating the amount and availability of VEGF.
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PMID:Nitric oxide synthase II gene disruption: implications for tumor growth and vascular endothelial growth factor production. 1130 6

It is generally accepted that the vascular endothelial growth factor (VEGF) signal system has no role in the maintenance of normal blood cell formation, although it obviously regulates the development of primitive hematopoiesis during an early stage of embryogenesis. The VEGF signaling pathway, however, might have some role in malignant hematopoiesis, since malignant hematopoietic cells, including acute myeloid leukemia (AML) cells, have been shown to express VEGF and its receptors. In endothelial cells, the VEGF/Flk-1/KDR signal system is a very important generator of nitric oxide (NO) through the activation of its downstream effectors phosphatidylinositol-3-OH-kinase (PI3-K), Akt kinase and endothelial NO synthase (eNOS). It is known that NO regulates hematopoiesis and modulates AML cell growth. The role of the VEGF signaling pathway in the control of AML cell growth through eNOS, however, has not been studied. By using the OCI/AML-2 cell line, which expresses VEGF receptor-2, ie Flk-1/KDR, eNOS and VEGF, as analyzed by flow cytometry, and produces VEGF into growth medium, as analyzed by ELISA, we showed that the Akt kinase and NOS activities in these cells were decreased by the inhibitors of VEGF, Flk-1/KDR and PI3-K, and NOS activity also by the direct inhibitor of NOS. The decreased NOS activity led to inhibition of clonogenic cell growth and, to some extent, induction of apoptosis. We also found that blast cells of bone marrow samples randomly taken from 14 AML patients uniformly expressed Flk-1/KDR and to varying degrees eNOS and VEGF, as analyzed by immunohistochemistry. We conclude that autocrine VEGF through Flk-1/KDR, by activating eNOS to produce NO through PI3-K/Akt kinase, maintains clonogenic cell growth in the OCI/AML-2 cell line. Since the patient samples did not express VEGF in all cases, it is possible that in vivo the regulatory connection between these two signal systems is also mediated via endocrine VEGF in addition to autocrine or paracrine VEGF.
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PMID:Regulation of the acute myeloid leukemia cell line OCI/AML-2 by endothelial nitric oxide synthase under the control of a vascular endothelial growth factor signaling system. 1151 4

The prognostic significance of vessel quantification in human solid tumours is still debated, due to the presence of multiple factors modulating neoangiogenesis and the invasiveness of neoplastic cells. This study examined ten supraglottic squamous carcinomas, ten non-small cell lung carcinomas (three squamous, five bronchioloalveolar, two adenocarcinomas), and nine classic (NOS) invasive ductal breast carcinomas. The properties studied in these tumours were vascularity; the immunohistochemical distribution of adhesion molecules such as alpha2beta1, alpha3beta1, alpha4beta1, alpha5beta1, alpha6beta4, and ICAM-1 in endothelial cells; extracellular matrix proteins (ECMPs) and laminin alpha2 chain (merosin M chain) in basal membranes of vessels; and gene expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF2), and transforming growth factor beta1 (TGFbeta1), by in situ hybridization. Independently of tumour type and vascularity, laminin alpha2 chain expression was observed in the basal membranes of a limited proportion of vessels. In vitro experiments demonstrated laminin alpha2 chain expression mainly in early endothelial cell cultures, suggesting that laminin alpha2 chain expression in vivo can be considered a marker of early angiogenesis. Stromal and parenchymal vascularity was associated with laminin alpha2 chain expression in supraglottic carcinomas, whereas in the other tumours, laminin alpha2 chain-positive vessels were observed only in the stroma. In supraglottic carcinomas, VEGF-positive cells were mainly represented by neoplastic cells, whereas in the other tumours, the great majority of VEGF-positive cells were macrophages and fibroblasts. FGF2- and TGFbeta1-positive cells were macrophages and fibroblasts in all tumours. These observations suggest that in addition to the quantification and distribution of vessels, evaluation of their maturation may contribute to a better understanding of the role of angiogenesis in the growth and spread potential of solid tumours. In this regard, in supraglottic carcinomas, parenchymal angiogenesis seems to be regulated mainly by neoplastic cells, which may help to explain their high metastatic potential; in solid tumours of different histogenesis, different cells might be responsible for modulating tumour angiogenesis.
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PMID:Laminin alpha2 chain (merosin M chain) distribution and VEGF, FGF(2), and TGFbeta1 gene expression in angiogenesis of supraglottic, lung, and breast carcinomas. 1159 99

The pathogenesis of cigarette smoke-induced pulmonary hypertension is not well characterized. We used RT-PCR to examine gene expression of nitric oxide synthase 2 (NOS-2), nitric oxide synthase 3 (NOS-3), endothelin, and vascular endothelial growth factor (VEGF) and its flk-1 receptor (VEGF-R) in main pulmonary arteries and in intraparenchymal arteries microdissected from alcohol-fixed paraffin blocks. The main pulmonary artery and intraparenchymal vessels responded in a similar fashion, with up-regulation of endothelin, VEGF, and VEGF-R gene expression evident by 2 hours after smoke exposure. Up-regulation of gene expression was still present at 24 hours after exposure, and at this time there was also a small increase in NOS-2. As a comparison, we examined the trachea and microdissected intraparenchymal airways and found up-regulation of endothelin and NOS-2 at 2 hours and additional up-regulation of NOS-3 at 24 hours. These findings suggest that the pulmonary vasculature very rapidly responds to cigarette smoke with up-regulation of mediators that control vascular cell proliferation and vascular constriction. These changes support the idea that pulmonary hypertension in cigarette smokers reflects a direct effect of smoke on the vasculature. The pattern of response in the vessels is distinctly different from that in the airways.
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PMID:Cigarette smoke induces rapid changes in gene expression in pulmonary arteries. 1237 73


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