title: Role of JunB in adenosine A2B receptor-mediated vascular endothelial growth factor production.
abstract: Interstitial adenosine stimulates neovascularization in part through A2B adenosine receptor-dependent upregulation of vascular endothelial growth factor (VEGF). In the current study, we tested the hypothesis that A2B receptors upregulate JunB, which can contribute to stimulation of VEGF production. Using the human microvascular endothelial cell line, human mast cell line, mouse cardiac Sca1-positive stromal cells, and mouse Lewis lung carcinoma (LLC) cells, we found that adenosine receptor-dependent upregulation of VEGF production was associated with an increase in VEGF transcription, activator protein-1 (AP-1) activity, and JunB accumulation in all cells investigated. Furthermore, the expression of JunB, but not the expression of other genes encoding transcription factors from the Jun family, was specifically upregulated. In LLC cells expressing A2A and A2B receptor transcripts, only the nonselective adenosine agonist NECA (5'-N-ethylcarboxamidoadenosine), but not the selective A2A receptor agonist CGS21680 [2-p-(2-carboxyethyl) phenylethylamino-5'-N-ethylcarboxamidoadenosine], significantly increased JunB reporter activity and JunB nuclear accumulation, which were inhibited by the A2B receptor antagonist PSB603 [(8-[4-[4-((4-chlorophenzyl)piperazide-1-sulfonyl)phenyl]]-1-propylxanthine]. Using activators and inhibitors of intracellular signaling, we demonstrated that A2B receptor-dependent accumulation of JunB protein and VEGF secretion share common intracellular pathways. NECA enhanced JunB binding to the murine VEGF promoter, whereas mutation of the high-affinity AP-1 site (-1093 to -1086) resulted in a loss of NECA-dependent VEGF reporter activity. Finally, NECA-dependent VEGF secretion and reporter activity were inhibited by the expression of a dominant negative JunB or by JunB knockdown. Thus, our data suggest an important role of the A2B receptor-dependent upregulation of JunB in VEGF production and possibly other AP-1-regulated events.
authors.affiliation: Divisions of Cardiovascular Medicine (S.R., Q.Z., I.F.) and Clinical Pharmacology (A.E.G., I.B.), and Departments of Cancer Biology (A.B., M.M.D.), Medicine (S.R., A.E.G., Q.Z., I.B., I.F.), and Pharmacology (I.B., I.F.), Vanderbilt University, Nashville, Tennessee.
authors.forename: Sergey
authors.initials: S
authors.lastname: Ryzhov
authors.forename: Asel
authors.initials: A
authors.lastname: Biktasova
authors.forename: Anna E
authors.initials: AE
authors.lastname: Goldstein
authors.forename: Qinkun
authors.initials: Q
authors.lastname: Zhang
authors.forename: Italo
authors.initials: I
authors.lastname: Biaggioni
authors.forename: Mikhail M
authors.initials: MM
authors.lastname: Dikov
authors.forename: Igor
authors.initials: I
authors.lastname: Feoktistov
mesh_terms: D000241:Adenosine / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006801:Humans; D051379:Mice; D009154:Mutation; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D043704:Receptor, Adenosine A2B / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C581727:JunB protein, human; C584097:JunB protein, mouse; D043704:Receptor, Adenosine A2B; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D000241:Adenosine