title: Identification of hypoxia-inducible factor HIF-1A as transcriptional regulator of the A2B adenosine receptor during acute lung injury.
abstract: Although acute lung injury (ALI) contributes significantly to critical illness, resolution often occurs spontaneously through endogenous pathways. We recently found that mechanical ventilation increases levels of pulmonary adenosine, a signaling molecule known to attenuate lung inflammation. In this study, we hypothesized a contribution of transcriptionally controlled pathways to pulmonary adenosine receptor (ADOR) signaling during ALI. We gained initial insight from microarray analysis of pulmonary epithelia exposed to conditions of cyclic mechanical stretch, a mimic for ventilation-induced lung disease. Surprisingly, these studies revealed a selective induction of the ADORA2B. Using real-time RT-PCR and Western blotting, we confirmed an up to 9-fold induction of the ADORA2B following cyclic mechanical stretch (A549, Calu-3, or human primary alveolar epithelial cells). Studies using ADORA2B promoter constructs identified a prominent region within the ADORA2B promoter conveying stretch responsiveness. This region of the promoter contained a binding site for the transcription factor hypoxia-inducible factor (HIF)-1. Additional studies using site-directed mutagenesis or transcription factor binding assays demonstrated a functional role for HIF-1 in stretch-induced increases of ADORA2B expression. Moreover, studies of ventilator-induced lung injury revealed induction of the ADORA2B during ALI in vivo that was abolished following HIF inhibition or genetic deletion of Hif1a. Together, these studies implicate HIF in the transcriptional control of pulmonary adenosine signaling during ALI.
authors.affiliation: Mucosal Inflammation Program, Department of Anesthesiology, University of Colorado, Aurora, CO 80045.
authors.forename: Tobias
authors.initials: T
authors.lastname: Eckle
authors.forename: Emily M
authors.initials: EM
authors.lastname: Kewley
authors.forename: Kelley S
authors.initials: KS
authors.lastname: Brodsky
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Tak
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bonney
authors.forename: Merit
authors.initials: M
authors.lastname: Gobel
authors.forename: Devon
authors.initials: D
authors.lastname: Anderson
authors.forename: Louise E
authors.initials: LE
authors.lastname: Glover
authors.forename: Ann K
authors.initials: AK
authors.lastname: Riegel
authors.forename: Sean P
authors.initials: SP
authors.lastname: Colgan
authors.forename: Holger K
authors.initials: HK
authors.lastname: Eltzschig
mesh_terms: D055371:Acute Lung Injury / Q000378:metabolism / Q000503:physiopathology*; D000241:Adenosine / Q000502:physiology; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000502:physiology; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000172:deficiency / Q000502:physiology*; D008168:Lung / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic / Q000235:genetics; D043704:Receptor, Adenosine A2B / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D013314:Stress, Mechanical; D014158:Transcription, Genetic; D055397:Ventilator-Induced Lung Injury / Q000503:physiopathology*
chemical_list: C497442:HIF1A protein, human; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D043704:Receptor, Adenosine A2B; D000241:Adenosine