Adenosine released by cells in injurious or hypoxic environments has tissue-protecting and anti-inflammatory effects, which are also a result of modulation of macrophage functions, such as vascular endothelial growth factor (VEGF) production. As VEGF is a well-known target of hypoxia-inducible factor 1 (HIF-1), we hypothesized that adenosine may activate HIF-1 directly. Our studies using subtype-specific adenosine receptor agonists and antagonists showed that by activating the A(2A) receptor, adenosine treatment induced HIF-1 DNA-binding activity, nuclear accumulation, and transactivation capacity in J774A.1 mouse macrophages. Increased HIF-1 levels were also found in adenosine-treated mouse peritoneal macrophages. The HIF-1 activation induced by the A(2A) receptor-specific agonist CGS21680 required the PI-3K and protein kinase C pathways but was not mediated by changes in iron levels. Investigation of the molecular basis of HIF-1 activation revealed the involvement of transcriptional and to a larger extent, translational mechanisms. HIF-1 induction triggered the expression of HIF-1 target genes involved in cell survival (aldolase, phosphoglycerate kinase) and VEGF but did not induce inflammation-related genes regulated by HIF-1, such as TNF-alpha or CXCR4. Our results show that the formation of adenosine and induction of HIF-1, two events which occur in response to hypoxia, are linked directly and suggest that HIF-1 activation through A(2A) receptors may contribute to the anti-inflammatory and tissue-protecting activity of adenosine.

Adenosine A2a receptor-mediated, normoxic induction of HIF-1 through PKC and PI-3K-dependent pathways in macrophages. / DE PONTI C; CARINI R; ALCHERA E; M. NITTI; LOCATI M; ALBANO E; CAIRO G; TACCHINI L. - In: JOURNAL OF LEUKOCYTE BIOLOGY. - ISSN 0741-5400. - STAMPA. - 82(2)(2007), pp. 392-402.

Adenosine A2a receptor-mediated, normoxic induction of HIF-1 through PKC and PI-3K-dependent pathways in macrophages.

NITTI, MARIAPAOLA;
2007

Abstract

Adenosine released by cells in injurious or hypoxic environments has tissue-protecting and anti-inflammatory effects, which are also a result of modulation of macrophage functions, such as vascular endothelial growth factor (VEGF) production. As VEGF is a well-known target of hypoxia-inducible factor 1 (HIF-1), we hypothesized that adenosine may activate HIF-1 directly. Our studies using subtype-specific adenosine receptor agonists and antagonists showed that by activating the A(2A) receptor, adenosine treatment induced HIF-1 DNA-binding activity, nuclear accumulation, and transactivation capacity in J774A.1 mouse macrophages. Increased HIF-1 levels were also found in adenosine-treated mouse peritoneal macrophages. The HIF-1 activation induced by the A(2A) receptor-specific agonist CGS21680 required the PI-3K and protein kinase C pathways but was not mediated by changes in iron levels. Investigation of the molecular basis of HIF-1 activation revealed the involvement of transcriptional and to a larger extent, translational mechanisms. HIF-1 induction triggered the expression of HIF-1 target genes involved in cell survival (aldolase, phosphoglycerate kinase) and VEGF but did not induce inflammation-related genes regulated by HIF-1, such as TNF-alpha or CXCR4. Our results show that the formation of adenosine and induction of HIF-1, two events which occur in response to hypoxia, are linked directly and suggest that HIF-1 activation through A(2A) receptors may contribute to the anti-inflammatory and tissue-protecting activity of adenosine.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/228826
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