title: Sequential activation of JAKs, STATs and xanthine dehydrogenase/oxidase by hypoxia in lung microvascular endothelial cells.
abstract: Xanthine dehydrogenase/oxidase (XDH/XO) is associated with various pathological conditions related to the endothelial injury. However, the molecular mechanism underlying the activation of XDH/XO by hypoxia remains largely unknown. In this report, we determined whether the Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) signaling pathway is involved in hypoxia-induced activation of XDH/XO in primary cultures of lung microvascular endothelial cells (LMVEC). We found that hypoxia significantly increased interleukin 6 (IL6) production in a time-dependent manner in LMVEC. Hypoxia also markedly augmented phosphorylation/activation of JAKs (JAK1, JAK2 and JAK3) and the JAK downstream effectors STATs (STAT3 and STAT5). Hypoxia-induced activation of STAT3 was blocked by IL6 antibodies, the JAK inhibitor AG490 and the suppressor of cytokine signaling 3 (SOCS3), implying that hypoxia-promoted IL6 secretion activates the JAK/STAT pathway in LMVEC. Phosphorylation and DNA-binding activity of STAT3 were also inhibited by the p38 MAPK inhibitor SB203580 and the phosphatidylinositol 3-kinase inhibitor LY294002, suggesting that multiple signaling pathways involved in STAT activation by hypoxia. Importantly, hypoxia promoted XDH/XO activation in LMVEC, which was markedly reversed by inhibiting the JAK-STAT pathway using IL6 antibodies, AG490 and SOCS3. These data demonstrated that JAKs, STATs and XDH/XO were sequentially activated by hypoxia. These data provide the first evidence indicating that the JAK-STAT pathway is involved in hypoxia-mediated XDH/XO activation in LMVEC.
authors.affiliation: Institute of Respiratory Diseases, Xinqiao Hospital of Third Military Medical University, Chongqing 400037, PR China.
authors.forename: Guansong
authors.initials: G
authors.lastname: Wang
authors.forename: Pin
authors.initials: P
authors.lastname: Qian
authors.forename: Fannie R
authors.initials: FR
authors.lastname: Jackson
authors.forename: Guisheng
authors.initials: G
authors.lastname: Qian
authors.forename: Guangyu
authors.initials: G
authors.lastname: Wu
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D042783:Endothelial Cells / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis; D053612:Janus Kinases / Q000378:metabolism*; D008168:Lung / Q000098:blood supply; D009025:Morpholines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D050791:STAT Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction; D014968:Xanthine Dehydrogenase / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D002867:Chromones; D004791:Enzyme Inhibitors; D007093:Imidazoles; D015850:Interleukin-6; D009025:Morpholines; D011725:Pyridines; D050791:STAT Transcription Factors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D014968:Xanthine Dehydrogenase; D053612:Janus Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580