Search results for "Oxide"
showing 10 items of 6424 documents
High sensitivity of northern pike larvae to UV-B but no UV-photoinduced toxicity of retene
2003
In order to investigate whether increased UV-B radiation is a risk factor, a series of acute laboratory experiments was conducted with larval stages of the northern pike (Esox lucius L.), hatching in Nordic waters in May. Further, a comparative investigation on the acute phototoxicity of retene (7-isopropyl-1-methylphenanthrene), a PAH compound recently revealed to posses UV-B-induced phototoxicity in larval coregonids, was conducted with pike larvae. In semi-static experiment, larvae were pre-exposed to retene (3, 9, 30 and 82 microg/g), with relevant controls, for 24 h and then irradiated for 3 h once a day (two consecutive days) with three UV-B doses (CIE-weighted 1.0, 1.8 or 2.7 kJ/m2 p…
Apigenin‐induced nitric oxide production involves calcium‐activated potassium channels and is responsible for antiangiogenic effects
2007
Summary. Background: The dietary flavonoid apigenin (Api) has been demonstrated to exert multiple beneficial effects upon the vascular endothelium. The aim of this study was to examine whether Ca2+-activated K+ channels (KCa) are involved in endothelial nitric oxide (NO) production and antiangiogenic effects.Methods: Endothelial NO generation was monitored using a cyclic guanosine monophosphate radioimmunoassay. KCa activity and changes of the intracellular Ca2+ concentration [Ca2+]i were analyzed using the fluorescent dyes bis-barbituric acid oxonol, potassium-binding benzofuran isophthalate, and fluo-3. The endothelial angiogenic parameters measured were cell proliferation, [3H]-thymidine…
Differential roles of PKCα and PKCɛ in controlling the gene expression of Nox4 in human endothelial cells
2007
NADPH oxidases are major sources of superoxide in the vascular wall. This study investigates the role of protein kinase C (PKC) in regulating gene expression of NADPH oxidases. Treatment of human umbilical vein endothelial cells (HUVEC) and HUVEC-derived EA.hy 926 endothelial cells with phorbol 12-myristate 13-acetate (PMA) or phorbol 12,13-dibutyrate led to a PKC-dependent biphasic expression of the gp91phox homolog Nox4. A downregulation of Nox4 was observed at 6 h and an upregulation at 48 h after phorbol ester treatment. The early Nox4 downregulation was associated with a reduced superoxide production, whereas the late Nox4 upregulation was accompanied by a clear enhancement of superoxi…
Activation of protein kinase C alpha and/or epsilon enhances transcription of the human endothelial nitric oxide synthase gene.
1998
In primary human umbilical vein endothelial cells (HUVECs), incubation with phorbol-12-myristate-13-acetate (PMA) enhanced basal and bradykinin-stimulated nitric oxide production. In the HUVEC-derived cell line EA.hy 926, PMA and phorbol-12,13-dibutyrate stimulated endothelial nitric oxide synthase (NOS III) mRNA expression in a concentration- and time-dependent manner. Maximal mRNA expression (3.3-fold increase) was observed after 18 hr. NOS III protein and activity were increased to a similar extent. The specific protein kinase C (PKC) inhibitors bisindolylmaleimide I (1 microM), Gö 6976 [12-(2 cyanoethyl)-6,7,12, 13-tetrahydro-13-methyl-5-oxo-5H-indolo[2,3-a]pyrrolo-[3, 4-c]carbazole] (1…
Indomethacin enhances endothelial NO release — evidence for a role of PGI2 in the autocrine control of calcium-dependent autacoid production
1998
Objective: We studied whether NO or prostacyclin (PGI2), which are continuously released by endothelial cells, have autocrine/paracrine effects on the calcium-dependent autacoid production by modulating the intracellular Ca2+ concentration ([Ca2+]i). Methods: Histamine(His)-induced [Ca2+]i increases (Fura 2-method) and NO-dependent cGMP increase were measured in human umbilical vein endothelial cells (HUVECs) before and after cyclooxygenase inhibition or application of cAMP- and cGMP-elevating drugs. Results: 0.3 μM His increased endothelial [Ca2+]i from 77±2 nM to 418±59 nM. The His-induced [Ca2+]i increases were significantly attenuated following treatment with PGI2 (by 23%) and forskolin…
Human inducible nitric oxide synthase (iNOS) expression depends on chromosome region maintenance 1 (CRM1)- and eukaryotic translation initiation fact…
2012
Human inducible nitric oxide synthase (iNOS) is regulated on the expressional level mostly by post-transcriptional mechanisms modulating the mRNA stability. Another important step in the control of eukaryotic gene expression is the nucleocytoplasmic mRNA transport. Most cellular mRNAs are exported via the TAP/Nxt complex of proteins. However, some mRNAs are transported by a different mechanism involving the nuclear export receptor CRM1. Treatment of DLD-1 cells with the CRM1 inhibitor leptomycin B (LMB) or anti-CRM1 siRNAs reduced cytokine-induced iNOS expression. We could demonstrate that the iNOS mRNA is exported from the nucleus in a CRM1-dependent manner. Since CRM1 itself does not poss…
Post-transcriptional regulation of the human inducible nitric oxide synthase (iNOS) expression by the cytosolic poly(A)-binding protein (PABP).
2012
Affinity purification using the 3'-untranslated region (3'-UTR) of the human inducible nitric oxide synthase (iNOS) mRNA identified the cytosolic poly(A)-binding protein (PABP) as a protein interacting with the human iNOS 3'-UTR. Downregulation of PABP expression by RNA interference resulted in a marked reduction of cytokine-induced iNOS mRNA expression without changes in the expression of mRNAs coding for the major subunit of the RNA polymerase II (Pol 2A) or β2-microglobuline (β2M). Along with the mRNA also iNOS protein expression was reduced by siPABP-treatment, whereas in the same cells protein expression of STAT-1α, NF-κB p65, or GAPDH was not altered. Reporter gene analyses showed no …
Nitric oxide increases the decay of matrix metalloproteinase 9 mRNA by inhibiting the expression of mRNA-stabilizing factor HuR.
2003
Dysregulation of extracellular matrix turnover is an important feature of many inflammatory processes. Rat renal mesangial cells express high levels of matrix metalloproteinase 9 (MMP-9) in response to inflammatory cytokines such as interleukin-1 beta. We demonstrate that NO does strongly destabilize MMP-9 mRNA, since different luciferase reporter gene constructs containing the MMP-9 3' untranslated region (UTR) displayed significant reduced luciferase activity in response to the presence of NO. Moreover, by use of an in vitro degradation assay we found that the cytoplasmic fractions of NO-treated cells contained a higher capacity to degrade MMP-9 transcripts than those obtained from contro…
The untranslated region of exon 2 of the human neuronal nitric oxide synthase (NOS1) gene exerts regulatory activity.
2007
Expressional dysregulation of the human neuronal nitric oxide synthase (NOS1) gene represents an important mechanism in the pathogenesis of certain neuronal disease states. The structure and regulation of the human NOS1 gene is highly complex based on cell type- and stimulus-dependent usage of multiple exon 1 variants. Here we demonstrate that the untranslated region of exon 2 exerts promoter and enhancer functions as well, facilitated in large part by cooperative interaction of two conserved adjacent CREB/AP-1 binding sites. In human neuronal A673 cells, NOS1 expression is stimulated by several compounds which act through these sites, but also stimulate the combined promoter region of exon…
Involvement of KSRP in the post-transcriptional regulation of human iNOS expression–complex interplay of KSRP with TTP and HuR
2005
We purified the KH-type splicing regulatory protein (KSRP) as a protein interacting with the 3'-untranslated region (3'-UTR) of the human inducible nitric oxide (iNOS) mRNA. Immunodepletion of KSRP enhanced iNOS 3'-UTR RNA stability in in vitro-degradation assays. In DLD-1 cells overexpressing KSRP cytokine-induced iNOS expression was markedly reduced. In accordance, downregulation of KSRP expression increases iNOS expression by stabilizing iNOS mRNA. Co-immunoprecipitations showed interaction of KSRP with the exosome and tristetraprolin (TTP). To analyze the role of KSRP binding to the 3'-UTR we studied iNOS expression in DLD-1 cells overexpressing a non-binding mutant of KSRP. In these ce…