title: NADPH oxidase 4 mediates upregulation of type 4 phosphodiesterases in human endothelial cells.
abstract: The protective actions of prostacyclin (PGI(2) ) are mediated by cyclic AMP (cAMP) which is reduced by type 4 phosphodiesterases (PDE4) which hydrolyze cAMP. Superoxide (O2(-)) from NADPH oxidase (Nox) is associated with impaired PGI(2) bioactivity. The objective of this study, therefore, was to study the relationship between Nox and PDE4 expression in human umbilical vein endothelial cells (HUVECs). HUVECs were incubated with the thromboxane A(2) analog, U46619, 8-isoprostane F(2α) (8IP), or tumor necrosing factor alpha (TNFα) [±iloprost (a PGI(2) analog)] and the expression of PDE4A, B, C, and D and splice variants thereof assessed using Western blotting and qPCR and mRNA silencing of Nox4 and Nox5. Effects on cell replication and angiogenesis were also studied. U46619, 8IP, and TNFα increased the expression of Nox 4 and Nox 5 and all PDE4 isoforms as well as cell replication and tubule formation (index of angiogenesis), effects inhibited by mRNA silencing of Nox4 (but not Nox5) and iloprost and rolipram. These data demonstrate that upregulation of Nox4 leads to an upregulation of PDE4A, B, and D and increased hydrolysis of cAMP which in turn augments cell replication and angiogenesis. This mechanism may be central to vasculopathies associated with endothelial dysfunction since the PGI(2)-cAMP signaling axis plays a key role in mediating functions that include hemostasis and angiogenesis.
authors: Bristol Heart Institute, University of Bristol, Bristol, UK.
authors: Saima
authors: S
authors: Muzaffar
authors: Jamie Y
authors: JY
authors: Jeremy
authors: Gianni D
authors: GD
authors: Angelini
authors: Nilima
authors: N
authors: Shukla
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D017398:Alternative Splicing; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000235:genetics / Q000378:metabolism*; D015237:Dinoprost / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000378:metabolism; D020868:Gene Silencing; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D016285:Iloprost / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D000074663:NADPH Oxidase 4; D000074664:NADPH Oxidase 5; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C075750:8-epi-prostaglandin F2alpha; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D015237:Dinoprost; D000074663:NADPH Oxidase 4; D000074664:NADPH Oxidase 5; D019255:NADPH Oxidases; C498910:NOX4 protein, human; C431571:NOX5 protein, human; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D016285:Iloprost