1. Role of HIF-1alpha in proton-mediated CXCR4 down-regulation in endothelial cells
- Author
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Maurizio C. Capogrossi, Gabriele Toietta, Daniele Porcelli, Carlo Gaetano, Chiara Cencioni, Valeria Ambrosino, Silvia Truffa, Roberta Melchionna, Ombretta Pozzoli, Marta Romani, Daniela D'Arcangelo, Claudia Cappuzzello, Antonella Mangoni, Monica Napolitano, Melchionna, R, Romani, M, Ambrosino, V, D'Arcangelo, D, Cencioni, C, Porcelli, D, Toietta, G, Truffa, S, Gaetano, C, Mangoni, A, Pozzoli, O, Cappuzzello, C, Capogrossi, M, and Napolitano, M
- Subjects
Male ,Chromatin Immunoprecipitation ,Receptors, CXCR4 ,Time Factors ,Transcription, Genetic ,Physiology ,Response element ,Down-Regulation ,Apoptosis ,Biology ,Transfection ,Ammonium Chloride ,Chemokine receptor ,Mice ,Physiology (medical) ,Transcriptional regulation ,Gene silencing ,Animals ,Humans ,RNA, Messenger ,Phosphorylation ,Promoter Regions, Genetic ,Cells, Cultured ,Binding Sites ,Effector ,Chemotaxis ,HIF-1 ,Endothelial Cells ,Hydrogen-Ion Concentration ,Hypoxia-Inducible Factor 1, alpha Subunit ,Cell Hypoxia ,Chemokine CXCL12 ,Cell biology ,Endothelial stem cell ,Disease Models, Animal ,Acidosi ,Biochemistry ,Chemokine ,Mutation ,RNA Interference ,Cardiology and Cardiovascular Medicine ,Acidosis ,Chromatin immunoprecipitation - Abstract
AimsAcidification is associated with a variety of pathological and physiological conditions. In the present study, we aimed at investigating whether acidic pH may regulate endothelial cell (EC) functions via the chemokine receptor CXCR4, a key modulator of EC biological activities.Methods and resultsExposure of ECs to acidic pH reversibly inhibited mRNA and protein CXCR4 expression, CXCL12/stromal cell-derived factor (SDF)-1-driven EC chemotaxis in vitro, and CXCR4 expression and activation in vivo in a mouse model. Further, CXCR4 signalling impaired acidosis-induced rescue from apoptosis in ECs. The inhibition of CXCR4 expression occurred transcriptionally and was hypoxia-inducible factor (HIF)-1-dependent as demonstrated by both HIF-1 and HIF-1 dominant negative overexpression, by HIF-1 silencing, and by targeted mutation of the-29 to-25 hypoxia response element (HRE) in the-357/-59 CXCR4 promoter fragment. Moreover, chromatin immunoprecipitation (ChIP) analysis showed endogenous HIF-1 binding to the CXCR4 promoter that was enhanced by acidification.ConclusionThe results of the present study identify CXCR4 as a key player in the EC response to acidic pH and show, for the first time, that HRE may function not only as an effector of hypoxia, but also as an acidosis response element, and raise the possibility that this may constitute a more general mechanism of transcriptional regulation at acidic pH. © The Author 2009. For permissions please.
- Published
- 2009