Central role of Sp1-regulated CD39 in hypoxia/ischemia protection

• Published in: Blood 2009-01, Vol.113 (1), p.224-232
• Main Authors: Eltzschig, Holger K., Köhler, David, Eckle, Tobias, Kong, Tianqing, Robson, Simon C., Colgan, Sean P.
• Format: Article
• Language: English
• Subjects: Animals; Antigens, CD - genetics; Antigens, CD - metabolism; Apyrase - genetics; Apyrase - metabolism; Cells, Cultured; Disease Models, Animal; Endothelial Cells - cytology; Endothelial Cells - metabolism; Female; Gene Expression Regulation - physiology; Humans; Hypoxia - metabolism; Hypoxia - pathology; Hypoxia - physiopathology; Male; Mice; Mice, Inbred C57BL; Mutagenesis, Site-Directed; Myocardial Infarction - metabolism; Myocardial Infarction - pathology; Myocardial Infarction - physiopathology; Myocardial Reperfusion Injury - metabolism; Myocardial Reperfusion Injury - pathology; Myocardial Reperfusion Injury - physiopathology; Promoter Regions, Genetic - physiology; RNA, Messenger - metabolism; RNA, Small Interfering; Sp1 Transcription Factor - metabolism; Vascular Biology
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2008-06-165746

Hypoxia is common to several inflammatory diseases, where multiple cell types release adenine-nucleotides (particularly adenosine triphosphate/adenosine diphosphate). Adenosine triphosphate/adenosine diphosphate is metabolized to adenosine through a 2-step enzymatic reaction initiated by CD39 (ectonucleoside-triphosphate-diphosphohydrolase-1). Thus, extracellular adenosine becomes available to regulate multiple inflammatory endpoints. Here, we hypothesized that hypoxia transcriptionally up-regulates CD39 expression. Initial studies revealed hypoxia-dependent increases in CD39 mRNA and immunoreactivity on endothelia. Examination of the human CD39 gene promoter identified a region important in hypoxia inducibility. Multiple levels of analysis, including site-directed mutagenesis, chromatin immunoprecipitation, and inhibition by antisense, revealed a critical role for transcription-factor Sp1 in hypoxia-induction of CD39. Using a combination of cd39−/− mice and Sp1 small interfering RNA in in vivo cardiac ischemia models revealed Sp1-mediated induction of cardiac CD39 during myocardial ischemia. In summary, these results identify a novel Sp1-dependent regulatory pathway for CD39 and indicate the likelihood that CD39 is central to protective responses to hypoxia/ischemia.