title: Nitric oxide upregulation of caspase-8 mRNA expression in lung endothelial cells: role of JAK2/STAT-1 signaling.
abstract: We recently reported that nitric oxide (NO) modulates expression of multiple genes associated with apoptotic pathways, including expression of caspase-8. The objective of the present study is to determine whether the NO-induced expression of the caspase-8 gene is regulated via signal transducers and activators of transcription-1 (STAT-1) signaling. The confluent monolayers of pulmonary artery endothelial cells (PAEC) were incubated with or without (control) 1 mM NOC-18, a NO donor, at 37 degrees C for 0-24 h. In some experiments PAEC were pretreated with a Janus kinase (JAK-2) inhibitor, AG490 (20 microM). Exposure of PAEC to NO-increased relative levels of caspase-8 mRNA as determined using quantitative real time PCR. Relative levels of phosphorylated STAT-1 at Serine (Ser)-727, but not total STAT-1 expression in NO-exposed cells, were upregulated significantly compared to control cells. AG490 attenuated NO-induced phosphorylation of STAT-1 at Ser 727 and expression of caspase-8 mRNA, suggesting JAK2 plays a role in the induction of caspase-8 mRNA. The promoter of caspase-8 has four gamma-activated sequence (GAS) and two interferon-stimulated response element (ISRE) transcription factor-binding sites. NO enhanced the STAT-1 binding activity to GAS/ISRE. Suppression of STAT-1 expression attenuated NO-induced elevation of caspase-8 mRNA. These studies demonstrate that a NO-dependent increase in caspase-8 mRNA levels is associated with phosphorylation of STAT-1 at Ser-727 and STAT1 binding to the caspase-8 promoter in cultured PAEC.
authors.affiliation: Department of Medicine, University of Florida College of Medicine, Gainesville, FL 32608-1197, USA.
authors.forename: Liuzhe
authors.initials: L
authors.lastname: Li
authors.forename: Jianliang
authors.initials: J
authors.lastname: Zhang
authors.forename: Bilian
authors.initials: B
authors.lastname: Jin
authors.forename: Edward R
authors.initials: ER
authors.lastname: Block
authors.forename: Jawaharlal M
authors.initials: JM
authors.lastname: Patel
mesh_terms: D000818:Animals; D053181:Caspase 8 / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D053614:Janus Kinase 2 / Q000502:physiology*; D008168:Lung / Q000187:drug effects* / Q000201:enzymology; D009569:Nitric Oxide / Q000494:pharmacology*; D010766:Phosphorylation; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D020218:Response Elements; D050794:STAT1 Transcription Factor / Q000378:metabolism / Q000502:physiology*; D013552:Swine; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; D009569:Nitric Oxide; D053614:Janus Kinase 2; D053181:Caspase 8